Supporting Information

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1 S1 Supporting Information Convergent Stereoselective Synthesis of the Visual Pigment A2E Cristina Sicre, M. Magdalena Cid* Departamento de Química Orgánica, Universidade de Vigo, Campus Lagoas-Marcosende, 10 Vigo (Spain) General. Reagents and solvents were purchased as reagent-grade and used without further purification unless otherwise stated. Solvents were dried according to published methods 1 and distilled before use. All reactions were performed in oven-dried or flamedried glassware under an inert atmosphere of Ar unless otherwise stated. Chromatography refers to flash chromatography (FC) on SiO 2 0 ( mesh) from Merck or neutral Al 2 O 8 (~10 mesh) from Aldrich activated Brockmann III, head pressure of ca 0.2 bar. TLC: UV 24 SiO 2 -coated plates from Merck, visualization by UV light (24 nm) or by coloring with 1% ethanolic phosphomolybdic acid solution. MR spectra were recorded in a Bruker AMX400 (400.1 MHz and.1 MHz for proton and carbon respectively) spectrometer at 298 K with residual solvent peaks as internal reference and the chemical shifts are reported in δ [ppm], coupling constants J are given in [Hz] and the multiplicities assigned with DEPT experiments and expressed as follows: s = singlet, d = doublet, t = triplet, q = cuartet, m = multiplet. COSY, HMBC and HSQC methods were used to stablish atom connectivities. Electronic impact ionization (EI) and Fast atom bombardment (FAB) mass spectra were recorded on a VG-Autospec M instrument. Electrospray spectra were performed on a Bruker Daltonics APEX III FT-ICR (Fourier Transform Ion Cyclotron Resonance), equipped with a 7T actively shielded magnet, using an Apollo API electrospray ionization source. Infrared spectra (IR) were obtained on a JASCO FT/IR-4200 infrared spectrometer. Peaks are quoted in wave numbers (cm -1 ) and their relative intensities are reported as follows: s = strong, m = medium, w = weak. UV/VIS spectra were recorded on a Varian-CARY Bio Scan using MeOH as solvent and a 1 cm cell. Absorption maxima are reported in λ max [nm] and ε [M -1 cm -1 ]. Reactions carried out under dark were performed using amber glassware. Melting points (mp) were taken on a Stuart Scientific apparatus. Elemental analysis was performed using a Fisons EA-1108 analizer. High-performance liquid chromatography (HPLC) was performed with a Waters 10 machine with a dual-wave detector (00 and 290 nm). 1 Perrin, D.; Amarego, W. Purification of Laboratory Chemicals; Pergamon Press: Oxford 1998.

2 S2 2,4-Dibromopyridine (4) OH Br OH Br 4 2,4-Dihydroxypyridine (2.7 g, 24. mmol) and POBr ( g, 80.2 mmol) were heated in a Schlenk tube at 12 ºC for 4. h. After cooling to 2 ºC, the reaction mixture was carefully poured into water, basified to ph = 9 with aqueous ahco (sat) and extracted with CH 2 Cl 2. The combined extracts were dried over a 2 SO 4 (anh) and the solvent removed in vacuo. The residue was purified by flash chromatography (40:0, CH 2 Cl 2 /hexane) to give 4.9 g (8 % yield) of 2,4-dibromopyridine (4) as a white solid (mp = ºC, EtOH, lit 2-8. ºC) and 0.9 g (12%) of 2,,4-tribromopyridine as a white solid (mp = 8 ºC, EtOH, lit ºC). 4: 1 H-MR (CDCl ) δ 7.4 (dd, J =., 1. Hz, 1H, H ), 7.70 (d, J = 1. Hz, 1H, H ), 8.21 (d, J =. Hz, 1H, H ) ppm. 1 C- MR (CDCl ) δ 121. (CH), 12.8 (CH), 128. (C), 1. (C), 14. (CH) ppm. MS (EI+) m/z 29 (M + 81 [Br] 81 [Br], 7), 27 (M + 81 [Br] 79 [Br], 7), 2 (M + 79 [Br] 79 [Br], 40), 18 (97), 1 (). 2,,4-Tribromopyridine: 1 H-MR (CDCl ) δ 7.2 (d, J =.1 Hz, 1H, H ), 8.11 (d, J =.1 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ 12.9 (C), (CH), 1.7 (C), (C), (CH) ppm. MS (EI+) m/z (%) 19 (M + 81 [Br] 81 [Br] 81 [Br], ), 17 (M + 81 [Br] 81 [Br] 79 [Br], ), 1 (M + 81 [Br] 79 [Br] 79 [Br], 8), 1 (M + 79 [Br] 79 [Br] 79 [Br], ), 28 (4), 2 (91). 2-[(1E)--tert-Butyldimethylsilyloxi-2-methylprop-1-en-1-yl]-4-halopyridine X X Br M OTBS OTBS 4a X=Br 4b X=Cl M = B(OiPr) 2, ZnCl a X=Br b X=Cl Method A: Suzuki conditions. X=Br. To a cold (-78 ºC) solution of (E)-tert-butyl(-iodo-2- methylallyloxy)dimethylsilane (0.4 g, 1.44 mmol) in THF ( ml) in a Schlenk flask was added dropwise t BuLi (1.8 ml, 1.7 M in pentane,.0 mmol) and the mixture was stirred at -78 ºC for 0 min. Then, B(OiPr) (0.7 ml, 2.88 mmol) was added dropwise and the mixture was stirred at 0 ºC for 2 h. At this time, Pd(PPh ) 4 (78 mg, 0.07 mmol), a solution of 4a (0.19 g, 0.80 mmol) in THF ( ml) and a 10% aqueous TlOH ( ml,.2 mmol) solution were added sequentially and the mixture was stirred at 2 ºC until complete disappearance of dibromopyridine as observed by TLC and MR (10 h). The crude mixture was diluted with Et 2 O, filtered through a Celite plug and washed with an aqueous saturated ahco solution (2). The organic layer was dried over a 2 SO 4 (anh) and concentrated in vacuo. The residue was purified by column chromatography on silica gel (9:4 hexane/etoac) affording 0.19 g (70%) of a as a 2 Den Hertog, H. J. Rec. Trav. Chim., 1944,,

3 S yellow oil and 12 mg (4%) of 7 as a yellow oil. a: 1 H-MR (CD 2 Cl 2 ) δ 0.12 (s, H, Si(CH ) 2 ), 0.9 (s, 9H, tbu), (br. s, H, CH ), 4.19 (d, J = 0.7 Hz, 2H, H ' ),.1 (m, 1H, H 1' ), 7.2 (dd, J =. Hz, 1.8 Hz, 1H, H ), 7.9 (d, J = 1.8 Hz, 1H, H ), 8.8 (d, J =. Hz, 1H, H ) ppm. 1 C-MR (CD 2 Cl 2 ) δ -.1 (CH, Si(CH ) 2 ), 1.8 (CH, CH - C 2' ), 18.9 (C, C-tBu), 2. (CH, tbu), 8. (CH 2, C ' ), (CH, C 1' ), 124. (CH, C ), 127. (CH, C ), 12.9 (C, C 4 ), 14.1 (C, C 2' ), 10.4 (CH, C ), 19.2 (C, C 2 ) ppm. IR (neat, cm -1 ) 2929 (w, C-H), 28 (w, C-H), 19 (w), 10 (w), 14 (m), 141 (m), 14 (m), 1 (w), 122 (m), 117 (w), 1107 (m), 1084 (m), 4 (w), 88 (w), 8 (s), 77 (s), 710 (m), 70 (m). MS (EI+) m/z (%) 4 (M + 81 [Br], 21), 41 (M + 79 [Br], 21), 28 ([M-tBu] + 81 [Br], ), 284 ([M-tBu] + 79 [Br], 9), 212 (2), 210 (2), 7 (7), 7 (2). High resolution MS calc for C 1 H 24 OSi 81 Br 790 and C 1 H 24 OSi 79 Br 4810; found 794 and : 1 H-MR (CDCl ) δ 0.11 (s, H, Si(CH ) 2 ), 0.9 (s, 9H, tbu), 1.8 (s, H, CH ), 4.17 (s, 2H, H ' ),.44 (s, 1H, H 1' ), 7.12 (dd, J =.1 Hz, 1.2 Hz, 1H, H ), 7. (br. s, 1H, H ), 8.28 (d, J =.1 Hz, 1H, H ) ppm. 1 C- MR (CDCl ) δ -.4 (CH, Si(CH ) 2 ), 1.2 (CH, CH -C 2' ), 18.4 (C, C-tBu), 2.9 (CH, tbu), 7. (CH 2, C ' ), 119. (CH, C 1' ), (CH, C ), 127. (CH, C ), 142. (C, C 2 ), 14.7 (C, C 2' ), (C, C 4 ), (CH, C ) ppm. IR (neat, cm -1 ) 291 (w, C-H), 2929 (w, C-H), 28 (w, C-H), 10 (w), 182 (m), 124 (m), 142 (m), 1 (m), 122 (m), 1170 (w), 1108 (s), 1078 (s), (w), 989 (w), 84 (s), 77 (s). MS (EI+) m/z (%) 4 (M + 81 [Br], 2), 42 ([M-1] + 81 [Br], 11), 41 (M + 79 [Br], 2), 40 ([M-1] + 79 [Br], 11), 00 (), 298 (98), 28 ([M-tBu] + 81 [Br], 2), 284 ([M-tBu] + 79 [Br], 2), 117 (24), 11 (20), 7 (79), 7 (9). High resolution MS calc for C 1 H 24 OSi 81 Br 790 and C 1 H 24 OSi 79 Br 4810; found 781 and X=Cl. 8 mg (0.29 mmol) of 4b and 0.10 g (0.2 mmol) of (E)-tert-butyl(-iodo-2- methylallyloxy)dimethylsilane afforded, after 0 min at 2 ºC and further purification by column chromatography on silica gel (90:10 hexane/etoac), 1 mg (9%) of b as a yellow oil. b: 1 H-MR (CDCl ) δ 0.11 (s, 12H, Si(CH ) 2 ), 0.9 (s, 18H, tbu), 4 (s, H, CH -C 2' ), 4.19 (s, 2H, H ' ),. (s, 1H, H 1' ), 9 (dd, J =. Hz, 1.9 Hz, 1H, H ), 7.22 (d, J = 1.9 Hz, 1H, H ), 8.48 (d, J =. Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ -. (CH ), 1. (CH ), 18.4 (C), 2.9 (CH ), 7.9 (CH 2 ), (CH), (CH), (CH), 14.7 (C), (C), (CH), 18.7 (C) ppm. IR (neat, cm -1 ) ν 292 (m, C- H), 2929 (m, C-H), 28 (m, C-H), 12 (w), 171 (s), 14 (m), 14 (m), 1 (w), 122 (m), 1107 (s), 108 (s), (w), 8 (s), 774 (s), 78 (m), 7 (w). MS (EI+) m/z (%) 299 (M + 7 [Cl], 9), 298 ([M+1] + [Cl], ), 297 (M + [Cl], 2), 242 ([M-tBu] + 7 [Cl], 7), 240 ([M-tBu] [Cl], ), 1 ([M-OTBS] + [Cl], 42), 11 (22), 71 (). High resolution MS calc for C 1 H 24 7 ClOSi and C 1 H 24 ClOSi ; found and Method B: egishi conditions. X=Br. To a cold (-78 ºC) solution of (E)-tert-butyl(-iodo-2- methylallyloxy)dimethylsilane (. g, 11. mmol) in THF (2 ml) was added dropwise t BuLi (1.7 ml, 1.7 M in pentane, 2.4 mmol) and the mixture was stirred at -78 ºC for 0 min. Then, a solution of ZnCl 2 (2. g, 18.4 mmol) in THF (1 ml), drying ZnCl 2 previously by heating at 120 ºC under vacuum for 2 h, was added dropwise and the mixture was allowed to warm to 2 ºC for 1 h. This solution was cannulated to a solution of Pd(PPh ) 4 (0.4 g, 0.9 mmol) and 4a (1. g,.40 mmol) in

4 S4 THF (1 ml) in a Schlenk flask. Upon stirring for 20 h, the reaction was quenched with an aqueous saturated H 4 Cl solution. The aqueous phase was extracted with Et 2 O () and the combined organic extracts were washed with brine (1), dried over a 2 SO 4 (anh.) and concentrated in vacuo. The residue was purified by column chromatography on silica gel (9:4 hexane/etoac) affording 1. g (7%) of a as a yellow oil, 0.21 g (10%) of 7 as a yellow oil. 4-Bromo-2-[(1E)- -hidroxy-2-methyl-prop-1-en-1-yl]pyridine (8) Br Br OTBS 8 OH A solution of silylether (0.0 g, 0.87 mmol) in THF (.0 ml) was treated with nbu 4 F ( ml, 1 M in THF, 4 mmol) and the mixture was stirred for 0 min at 2 ºC. It was diluted with EtOAc and washed with an aqueous saturated ahco solution (2). The combined aqueous layers were extracted with EtOAc () and the resulting organic extracts washed with brine (2), dried over a 2 SO 4 (anh.) and concentrated in vacuo. The residue was purified by column chromatography on silica gel (0:40 hexane/etoac) affording 0.20 g (%) of 8 as a yellow oil. 1 H-MR (CD 2 Cl 2 ) δ 1. (br. s, 1H, OH), 2.10 (d, J = 1. Hz, H, CH ), 4.18 (s, 2H, H ' ),.0 (q, J = 1. Hz, 1H, H 1' ), 7.28 (dd, J =. Hz, 1.8 Hz, 1H, H ), 7.42 (d, J = 1.8 Hz, 1H, H ), 8.9 (d, J =. Hz, 1H, H ) ppm. 1 C-MR (CD 2 Cl 2 ) δ (CH, CH -C 2' ), 8.9 (CH 2, C ' ), 122. (CH, C 1' ), 124. (CH, C ), (CH, C ), (C, C 4 ), 14. (C, C 2' ), 10.4 (CH, C ), 18.9 (C, C 2 ) ppm. IR (acl, cm -1 ) 00- (br., O-H), 2912 (m, C-H), 284 (m, C- H), 18 (m), 19 (m), 17 (s), 142 (s), 14 (m), 18 (m), 107 (m), 1018 (m), 88 (m), 82 (m). MS (EI+) m/z (%) 20 ([M+1] + 81 [Br], 17), 229 (M + 81 [Br], ), 228 ([M+1] + 79 [Br], 7), 227 (M + 79 [Br], 74), 22 (4), 210 (77), 208 (9), 198 (4), 19 (1), 117 (98). High resolution MS calc for C 9 H 10 O 81 Br and C 9 H 10 O 79 Br ; found, y General procedure for Sonogashira reaction of 4-bromopyridines. TMS Br TMS OR + OR 9 10 To a Schlenk type flask charged with Pd(PPh ) 2 Cl 2 (4 mol%), CuI (4 mol%) and a solution of the bromopyridine ( mol%) in Et (0. M) was added (trimethylsilyl)acetylene (10 mol%). The solution was stirred at 10 ºC for 4 h.

5 S Finally, triethylamine was removed in vacuo and the residue was purified by column chromatography on silica gel. For R=TBS: 2-[(1E)--tert-Butyldimethylsilyloxi-2-methylprop-1-en-1-yl]-4-[2- trimethylsilyleth-1-yn-1-yl]pyridine (10a) 11 mg (0.47 mmol) of bromopyridine afforded, after purification by column chromatography on silica gel (9: hexane/etoac), 1 mg (97%) of 10a as an oil. 1 H- MR (CDCl ) δ 0.11 (s, H, Si(CH ) 2 ), 0.2 (s, 9H, Si(CH ) ), 0.9 (s, 9H, tbu), (br. s, H, CH -C 2' ), 4.19 (d, J = 0.7 Hz, 2H, H ' ),. (m, 1H, H 1' ), 9 (dd, J =.1 Hz, 1.4 Hz, 1H, H ), 7.2 (br. s, 1H, H ), 8. (d, J =.1 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ -. (CH ), -0. (CH ), 1. (CH ), 18.4 (C), 2.9 (CH ), (CH 2 ), 99.0 (C), 102. (C), 12 (CH), (CH), 12.1 (CH), 1 (C), 14.1 (C), (CH), 17. (C) ppm. MS (EI+) m/z (%) 0 ([M+1] +, 20), 9 (M +, 0), 44 (), 0 (), 02 ([M-tBu] +, ), 228 ([M-OTBS] +, 1), 7 (22). High resolution MS calc C 20 H OSi ; found For R=H: 2-[(1E)--Hidroxy-2-methylprop-1-en-1-yl]-4-[2-trimethylsilyleth-1-yn- 1-yl]pyridine (10c) 1. g (.71 mmol) of bromopyridine 8 afforded, after purification by column chromatography on silica gel (0:8:2 EtOAc/hexane/Et ), 1. g (9%) of 10c as an oil. 1 H-MR (CDCl ) δ 0.2 (s, 9H, Si(CH ) ), 0 (s, H, CH ), 4.1 (s, 2H, H ' ),.7 (s, 1H, H 1' ), 7.10 (d, J =.0 Hz, 1H, H ), 7.2 (s, 1H, H ), 8.48 (d, J =.0 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ -0. (CH ), 1.4 (CH ), 7.8 (CH 2 ), 99.4 (C), (C), 122. (CH), 1 (CH), 12.1 (CH), 11. (C), 14.8 (C), (CH), 1.9 (C) ppm. IR (neat, cm -1 ) (br, OH), 298 (w, C-H), 2901 (w, C-H), 287 (w, C-H), 212 (w), 188 (m), 14 (w), 148 (w), 120 (m), 1170 (w), 107 (w), 94 (m), 89 (s), 78 (m), 702 (w), 47 (w). MS (EI+) m/z (%) 24 ([M+1] +, 20), 24 (M +, ), 244 ([M-1] +, 7), 20 (19), 228 (14), 227 (18), 22 (), 21 (2), 214 (1). High resolution MS calc for C 14 H 19 OSi 24.12; found Sonogashira reaction of 4-chloropyridine. TMS Cl TMS OTBS + SnMe OR b 9b 10a To a solution of (trimethylsilyl)acetylene (0.011 ml, 0.08 mmol) in THF (0. ml) in a Schlenk flask at -78 ºC was added dropwise n-buli (0.049 ml, 1.48 M in hexane, 0.07 mmol) and the mixture was stirred at -78 ºC for 0 min. Then, Me SnCl (14 mg, 0.07 mmol) was added and the mixture was stirred at -78 ºC for 2 h. At this time, the solvent was removed in vacuo and a solution of b (19 mg, 0.0 mmol) in toluene (0. ml) followed by Pd(PPh ) 4 (7 mg, 0.00 mmol) were added. The reaction mixture was

6 S stirred at ºC overnight. Finally, it was allowed to cool to 2 ºC and filtered through a Celita plug washing with EtOAc. The solvent was removed in vacuo and the residue was purified by column chromatography on silica gel (9: hexane/etoac) affording 11 mg (48%) of 10a and 9.9 mg (2%) of b. 4-Ethynyl-2-[(1E)--hidroxy-2-methylprop-1-en-1-yl]pyridine (10b) TMS OTBS OH 10a 10b A solution of silylether 10a (9 mg, 0.19 mmol) in THF (1. ml) was treated with nbu 4 F (0.4 ml, 1 M in THF, 0.4 mmol ) and the mixture was stirred for 2 h at 2 ºC. It was diluted with EtOAc and washed with an aqueous saturated ahco solution (2). The combined aqueous layers were extracted with EtOAc (x) and the resulting organic extracts washed with brine (2), dried over a 2 SO 4 and concentrated in vacuo. The residue was purified by column chromatography on silica gel (0:40 hexane/etoac) affording 2 mg (7%) of 10b as an oil. 1 H-MR (CDCl ) δ 2 (br s, H, CH -C 2' ),.14 (br s, 1H, OH),.2 (s, 1H, H 2" ), 4.18 (s, 2H, H ' ),.9 (d, J = 1. Hz, 1H, H 1' ), 7.1 (dd, J =.0 Hz, 1.4 Hz, 1H, H ), 7.29 (br s, 1H, H ), 8. (d, J =.0 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ 1. (CH ), 8.1 (CH 2 ), 81.2 (C), 81.4 (CH), 122. (CH), 12.2 (CH), 12.4 (CH), 10.4 (C), 14.8 (C), (CH), 1 (C) ppm. MS (EI+) m/z (%) 174 ([M+1] +, 1), 17 (M +, ), 172 ([M-1] +, ), 1 ([M-OH], 19), 1 (2), 14 (8), 144 (44), 142 (8), 141 (). High resolution MS calc for C 11 H 11 O 1841; found 187. General procedure for Dess-Martin oxidation R R OH CHO To a solution of Dess-Martin periodinane (1. mol equiv) and pyridine ( mol equiv) in CH 2 Cl 2 (0. M) at 0 ºC was added, via cannula, a solution of the alcohol ( mol equiv) in CH 2 Cl 2 (1 M) and the reaction mixture was stirred at 0 ºC for 2 h. The reaction mixture was diluted with EtOAc and washed with saturated ahco aqueous solution (2) and saturated a 2 S 2 O aqueous solution (2). The combined aqueous layers were extracted with EtOAc and the resulting organic extracts dried over a 2 SO 4 (anh), and concentrated in vacuo. The residue was purified by column chromatography on silica gel.

7 S7 For R=H : 4-Ethynyl-2-[(1E)--formil-2-methylprop-1-en-1-yl]pyridine (11a) 2 mg (0.14 mmol) of alcohol 10b afforded, after purification by column chromatography on silica gel (8:1 hexane/etoac), 20 mg (79%) of 11a as a white solid (mp ºC, hexane/ch 2 Cl 2 ). 1 H-MR (CDCl ) δ 2.24 (d, J = 1.4 Hz, H, CH -C 2' ),.4 (s, 1H, H 2" ), 7.21 (m, 1H, H 1' ), 7.1 (dd, J =.0 Hz, 1.4 Hz, 1H, H ), 7.4 (br. s, 1H, H ), 8.70 (d, J =.0 Hz, 1H, H ), 9.4 (s, 1H, CHO) ppm. 1 C-MR (CDCl ) δ 1 (CH ), 80. (C), 82.4 (CH), 12.4 (CH), (CH), 10.9 (C), (C), 14. (CH), 10.0 (CH), 14.7 (C), 19. (CH) ppm. IR (neat, cm -1 ) 228 (s, C C), 284 (w, C-H), 1 (s, C=O), 18 (w), 10 (m), 118 (m), 1024 (m), 91 (m), 828 (m), 72 (m), 88 (m). MS (EI+) m/z (%) 172 ([M+1] +, 9), 171 (M +, 7), 14 (11), 142 (), 141 (0), 11 (10). High resolution MS calc for C 11 H 9 O 1784; found 178. For R=TMS: 2-[(1E)--Formil-2-methylprop-1-en-1-yl]-4-[2-trimethylsilyleth-1- yn-1-yl]pyridine (11b) 1. g (.24 mmol) of alcohol 10c afforded, after purification by column chromatography on neutral alumina Act III (8:1 hexane/etoac), 1.4 g (92%) of 11b as a white solid (mp -7 ºC, hexane/ch 2 Cl 2 ). 1 H-MR (CD 2 Cl 2 ) δ 0.27 (s, 9H, Si(CH ) ), 2.22 (d, J = 1.2 Hz, H, CH -C 2' ), 7.19 (m, 1H, H 1' ), 7.27 (dd, J = 4.9 Hz, 1. Hz, 1H, H ), 7.1 (br s, 1H, H ), 8. (d, J = 4.9 Hz, 1H, H ), 9.1 (s, 1H, CHO) ppm. 1 C-MR (CD 2 Cl 2 ) δ -0.1 (CH ), 11. (CH ), 10 (C), 10 (C), 12. (CH), 128. (CH), 12. (C), 142. (C), 14.9 (CH), 10.4 (CH), 1. (C), 19.0 (CH) ppm. IR (neat, cm -1 ) 17 (s, C=O), 177 (m), 1 (w), 14 (w), 141 (w), 14 (w), 1297 (w), 120 (m), 1178 (m), 102 (m), 99 (m), 894 (w), 89 (s), 71 (m), 701 (m), 4 (m). MS (EI+) m/z (%) 244 ([M+1] +, 1), 24 (M +, 7), 228 (11), 21 (19), 214 (), 14 (8), 99 (9), 8 (), 7 (1). High resolution MS calc for C 14 H 17 OSi ; found Anal. calcd (%) C 9.09, H 4,.7; found C 8.90, H 7,.7. 2-[(1E)-2-Methylbut-1-en--yn-1-yl]-4-[2-trimethylsilyleth-1-yn-1-yl]pyridine (12a) TMS TMS CHO 11b 12a Trimethylsilyldiazomethane (0.0 ml, 2 M in hexane, 0.19 mmol) was added dropwise to a solution of LDA, prepared from diisopropylamine (0.027 ml, 0.19 mmol) and n- BuLi (0.19 ml, 1 M in hexane, 0.19 mmol ) in THF (0. ml), at -78 ºC and the mixture was stirred at this temperature for 0 min. A solution of the aldehyde ( mg, 0.1 mmol) in THF (0. ml) was then added dropwise at -78 ºC and the mixture was stirred

8 S8 under dark for h. After being quenched with water, the mixture was allowed to warm to 2 ºC and extracted with EtOAc. The organic extracts were dried over a 2 SO 4 (anh), and concentrated in vacuo. The residue was purified by column chromatography on silica gel (9:2:2 hexane/etoac/et ) affording 2 mg (%) of 12a as a white solid. 1 H-MR (CDCl ) δ 0.2 (s, 9H, Si(CH ) ), 2.1 (s, H, CH -C 2' ),.0 (s, 1H, H 4' ),.81 (s, 1H, H 1' ), 7.1 (d, J =.0 Hz, 1H, H ), 7.22 (s, 1H, H ), 8. (d, J =.0 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ -0. (CH ), 19.4 (CH ), 77.4 (CH), 87.2 (C), 99.7 (C), 10 (C), 12. (CH), 124. (C), 12.7 (CH), 11. (C), (CH), (CH), 1.7 (C) ppm. IR (acl, cm -1 ) 297 (m, C C-H), 298 (m, C-H), 292 (m, C-H), 284 (w, C-H), 18 (m), 14 (w), 147 (w), 121 (m), 942 (w), 847 (s), 70 (w). MS (EI+) m/z (%) 240 ([M+1] +, 0), 29 (M +, ), 28 ([M-H] +, 99), 224 (49), 180 (2), 1 ([M- TMS] +, 14). High resolution MS (FAB + ) calc for C 1 H 18 Si ; found UV (MeOH) λ max = 22 nm (ε 14900), 248 nm (ε 2000), 28 nm (ε 2200), 09 nm (ε 00). 4-Ethynyl-2-[(1E)-2-methylbut-1-en--yn-1-yl]pyridine (12b) TMS CHO 11b 12b A solution of triphenylphosphine (1.1 g, 4.11 mmol) in CH 2 Cl 2 (.0 ml) was added to a cooled (0 ºC) solution of carbon tetrabromide (0.8 g, mmol) in CH 2 Cl 2 (7. ml) under dark. This solution was stirred for 0 min at 0 ºC and then a solution of aldehyde 11b (0.2 g, mmol) in CH 2 Cl 2 (2. ml) was added dropwise. The reaction mixture darkens on addition. After stirring for 1 h the solvent was practically evaporated and filtered through a silica plug washing with 78:20:2 hexane/etoac/et. The resulting filtrate was concentrated under reduced pressure to give the corresponding dibromodiene, which was used without further purification. n-butyllithium (4.4 ml, 1.41 M in hexane,.17 mmol) was added dropwise to a solution of diisopropylamine (0.9 ml,.48 mmol) in THF ( ml) at 0 ºC. After 1 h, the resulting LDA solution was cooled to -78 ºC and transferred via cannula to a solution of the dibromodiene in THF (11.4 ml) at -78 ºC under dark. The reaction was stirred at this temperature for 1 min and the resulting dark solution was quenched with MeOH (.0 ml) and allowed to warm to room temperature. The reaction mixture was filtered through a Celite plug, washed with EtOAc and concentrated under reduced pressure. Purification was performed by flash chromatography on silica gel (90:8:2 hexane/etoac/et ) affording 0.14 g (80%) of 12b as a white solid. 1 H-MR (C D ) δ 2.4 (d, J = 1.4 Hz, H, CH -C 2' ), 2.7 (s, 1H, H 2" ), 2.7 (s, 1H, H 4' ),.9 (dd, J = 4.9 Hz, 1. Hz, 1H, H ),.7 (br s, 1H, H 1' ),.82 (br s, 1H, H ), 8.2 (d, J = 4.9 Hz, 1H, H ) ppm. 1 C-MR (C D ) δ 19.8 (CH, CH -C 2' ), 78.1 (CH, C 4' ), 81. (C, C 1" ), 81. (CH, C 2" ), 87.7 (C, C ' ), 12. (CH, C ), 12. (C, C 2' ), 127. (CH, C ), 10.4 (C, C 4 ), 14.9 (CH, C 1' ), 149. (CH, C ), 1.4 (C, C 2 ) ppm. IR (neat, cm -1 ) 270 (s, C C-H), 2920 (w, C-H), 211 (w), 118 (m), 182 (s), 1 (s), 147 (m), 14 (w), 19 (m), 10 (w), 122 (m), 1148 (m), 1104 (m), 92 (w), 901 (s), 89 (s), 771 (m). MS (EI+)

9 S9 m/z (%) 17 (M +, 7), 1 ([M-1] +, 10), 7 (), 7 (), 7 (), 71 (4), 9 (). High resolution MS calc for C 12 H 9 17; found 178. UV (MeOH) λ max = 2 nm (ε 14800), 244 nm (ε 1900), 2 nm (ε 12200), 07 nm (ε ). 2-[(1E,E)-4-Tributylstannyl-2-methylbuta-1,-dien-1-yl]-4-[(1E)-2- (tributylstannyl)eth-1-en-1-yl]pyridine () SnBu SnBu + SnBu 12b 1 SnBu To a solution of hexabutylditin (0.7 ml, 1.44 mmol) in THF (2.9 ml) was added n- BuLi (0.91 ml, 1.8 M in hexane, 1.44 mmol) at -78 ºC. The solution was stirred for 0 min at -40 ºC. Then the mixture was added via cannula to a suspension of CuC (4 mg, 0.72 mmol) in THF (0.1 ml) at -78 ºC under dark. The solution was stirred at -40 ºC for min. Dried MeOH (1. ml) was added at -78 ºC and the temperature was allowed to warm to -40 ºC. After 1 min, a solution of the alkyne 12b (0.0 g, 0.18 mmol) in THF (0.2 ml) was added dropwise. The dark solution was stirred for min and then quenched with dried MeOH (2 ml). After 1 min water (2 ml) was added and the reaction mixture allowed to warm to 2 ºC over 1 min. Then, it was extracted with diethyl ether and the organic layer was washed with brine, dried over a 2 SO 4, filtered, and concentrated in vacuo. Purification was performed by flash chromatography on silica gel (98:2 hexane/et, then hexane) affording 0.10 g (7%) of a 2.8:1 mixture of 2-[(1E,E)-4-tributylstannyl-2-(methylbuta-1,-dienyl)]-4-[(E)-2- (tributylstannyl)vinyl]pyridine () and 2-[(1E)--tributylstannyl-2-methylbuta-1,-dien- 1-yl]-4-[(1E)-2-(tributylstannyl)eth-1-en-1-yl]pyridine (1) as a yellow oil. The mixture was separated by HPLC [Waters Spherisorb s H 2, mm, 70:0 hexane/ch 2 Cl 2, flow: 1.8 ml/min, detector: UV 00 nm]. : 1 H-MR (CD 2 Cl 2 ) δ 0.91 (t, J = 7.2 Hz, 18H, SnCH 2 CH 2 CH 2 CH ), 0.9- (m, 12H, SnCH 2 CH 2 CH 2 CH ), -1.9 (m, 12H, SnCH 2 CH 2 CH 2 CH ), 1.2- (m, 12H, SnCH 2 CH 2 CH 2 CH ), 2.27 (d, J = 0.9 Hz, H, CH -C 2' ),.48 (br s, 1H, H 1' ),. (d, J = 19.2 Hz, 2 J 1 H- 119 Sn = 7. Hz, 2 J 1 H- 117 Sn = 4.9 Hz, 1H, H 4' ),.77 (d, J = 19.2 Hz, J 1 H- 119 Sn J 1 H- 117 Sn 7. Hz, 1H, H ' ),.8 (d, J = 19. Hz, 1H, H 1" ), 9 (dd, J =.1 Hz, 1. Hz, 1H, H ), 7.20 (d, J = 19. Hz, 2 J 1 H- 119 Sn 2 J 1 H- 117 Sn 2.7 Hz, 1H, H 2" ), 7.2 (br s, J 1 H- 119 Sn = 2. Hz, J 1 H- 117 Sn = 0.4 Hz, 1H, H ), 8.2 (d, J =.1 Hz, 1H, H ) ppm. 1 C-MR (CD 2 Cl 2 ) δ 10.1 (CH 2, SnCH 2 CH 2 CH 2 CH ), 10.2 (CH 2, SnCH 2 CH 2 CH 2 CH ), 1. (CH, CH -C 2' ), 14.1 (CH, SnCH 2 CH 2 CH 2 CH ), (CH 2, SnCH 2 CH 2 CH 2 CH ), (CH 2, SnCH 2 CH 2 CH 2 CH ), 29.7 (CH 2, SnCH 2 CH 2 CH 2 CH ), (CH 2, SnCH 2 CH 2 CH 2 CH ), (CH, C ), 122. (CH, C ), 10.7 (CH, C 1' ), 11. (CH, C 4' ), 17.1 (CH, C 2" ), (C, C 2' ), 144. (CH, C 1" ), 1 (C, C 4 ), 10.0 (CH, C ), 11.8 (CH, C ' ), 18. (C, C 2 ) ppm. IR (acl, cm -1 ) 29 (s, C-H), 2924 (s, C-H), 281 (m, C-H), 190 (m), 18 (w), 140 (m), 17 (w), 1178 (w), 11 (w), 1072 (w), 984 (m), 87 (w), 77 (w), 72 (m). MS (FAB + ) m/z (%) 72 (20), 70 (2), 748 (22), 40 (2),

10 S10 48 (2), 179 (4), 177 (2), 17 (4), 172 (29), 170 (). High resolution MS (FAB + ) calc for C H 120 Sn 120 Sn 72.29; found UV (MeOH) λ max = 272 nm (ε 19000), 20 nm (ε 000). 1: 1 H-MR (CD 2 Cl 2 ) δ (m, 18H, SnCH 2 CH 2 CH 2 CH ), (m, 12H, SnCH 2 CH 2 CH 2 CH ), (m, 12H, SnCH 2 CH 2 CH 2 CH ), (m, 12H, SnCH 2 CH 2 CH 2 CH ), 2.29 (s, H, CH -C 2' ),.7 (d, J = 1.9 Hz, J 1 H- 119 Sn J 1 H- 117 Sn 2.7 Hz, 1H, H 4' -cis),.0 (d, J = 1.9 Hz, J 1 H- 119 Sn = 12.9 Hz, J 1 H- 117 Sn = 129. Hz, 1H, H 4' -trans),.2 (s, 1H, H 1' ),.84 (d, J = 19. Hz, 1H, H 1" ), 8 (d, J =.1 Hz, 1H, H ), 7.14 (s, 1H, H ), 7.19 (d, J = 19. Hz, 1H, H 2" ), 8.1 (d, J =.1 Hz, 1H, H ) ppm. 1 C-MR (CD 2 Cl 2 ) δ 10.2 (CH 2, SnCH 2 CH 2 CH 2 CH ), 1 (CH 2, SnCH 2 CH 2 CH 2 CH ), 14.1 (CH, SnCH 2 CH 2 CH 2 CH ), 1.7 (CH, CH -C 2' ), (CH 2, SnCH 2 CH 2 CH 2 CH ), 27.9 (CH 2, SnCH 2 CH 2 CH 2 CH ), 29. (CH 2, SnCH 2 CH 2 CH 2 CH ), 29.9 (CH 2, SnCH 2 CH 2 CH 2 CH ), (CH, C ), (CH, C ), 12.8 (CH 2, C 4' ), 128. (CH, C 1' ), 1 (CH, C 2" ), 144. (CH, C 1" ), 1 (C, C 4 ), 147. (C, C 2' ), (CH, C ), 18.4 (C, C 2 ), 18.8 (C, C ' ) ppm. IR (acl, cm -1 ) 29 (s, C-H), 2924 (s, C-H), 282 (m, C- H), 191 (m), 18 (w), 141 (m), 17 (w), 1072 (w), 98 (w), 910 (w), 89 (w), 84 (w), 77 (w), 8 (m), 71 (m). MS (FAB + ) m/z (%) 72 (10), 70 (14), 748 (11), 92 (22), 90 (20), 290 (24), 288 (21), 281 (1), 2 (22), 221 (1), 207 (4), 179 (98), 177 (97), 17 (1), 172 (1), 170 (). High resolution MS (FAB + ) calc for C H 120 Sn 120 Sn 72.29; found UV (MeOH) λ max = 22 nm (ε ), 27 nm (ε 20900), 18 nm (ε 00). 2-[(1E,E,E,7E)-2,-Dimethyl-8-(2,,-trimethylcyclohex-1-en-1-yl)octa-1,,,7- tetraen-1-yl]-4-[(1e,e,e)-4-methyl--(2,,-trimethylcyclohex-1-en-1-yl)hexa- 1,,-trien-1-yl]pyridine (14) SnBu SnBu + I 1 SnBu (mixed with 1) 2 Method A: PdCl 2 (PhC) 2 (4 mg, mmol) was added to a solution of the iodide 2 (9 mg, 0.0 mmol) in DMF (.0 ml) and the resulting mixture was thoroughly degassed using freeze-thaw cycles (). After min at 2 ºC, a solution of a 4.:1 mixture of stannanes and 1 (7 mg, 0.10 mmol) and (ipr) 2 Et (0.10 ml, 0.0 mmol) in THF (.0 ml), previously thoroughly degassed using freeze-thaw cycles (), was added followed by BHT (trace). After stirring for 1 h, another portion of PdCl 2 (PhC) 2 (2 mg, 0.00 mmol) was added and the mixture was stirred for 1 h at 2 ºC. Then, an aqueous saturated KF solution was added, the layers were separated after 0 min of stirring and the aqueous layer was extracted with EtOAc (). The combined 14

11 S11 organic layers were washed with brine () and KF (1), dried over a 2 SO 4 and the solvent was removed. The residue was purified by column chromatography on neutral alumina Act III (99:1 hexane/etoac) affording 22 mg (0%) of 14 as a bright yellow solid and 1. Method B: To a solution of 2 ( mg, 0.17 mmol), Pd 2 dba (4 mg, mmol) and AsPh (11 mg, 0.04 mmol) in MP (0.7 ml) under dark previously thoroughly degassed using freeze-thaw cycles (), was added a degassed solution of a 1:1 mixture of and 1 (42 mg, 0.0 mmol) in MP (0.7 ml) and BHT (trace). The reaction mixture was stirred at 2 ºC for 8 h, when another portion of Pd 2 dba (4 mg, mmol) and AsPh (11 mg, 0.04 mmol) was added. It was stirred 2 h at 2 ºC and then, an aqueous saturated KF solution was added, the layers were separated after 0 min of stirring and the aqueous layer was extracted with EtOAc (). The combined organic layers were washed with brine () and KF (1), dried over a 2 SO 4 (anh.) and the solvent was removed. The residue was purified by column chromatography on neutral alumina Act III (99:1 hexane/etoac) affording 0.02 g (9%) of 14 as a bright yellow solid and traces of 1. 14: 1 H-MR (CDCl ) δ 4 (s, 12H, 2 CH -C 12" and 2 CH -C 14' ), 1.47 (m, 4H, (CH 2 ) 11" and (CH 2 ) 1' ), 1. (m, 4H, (CH 2 ) 9" and (CH 2 ) 11' ), 1.7 (s, H, CH -C 8" and CH -C 10' ), 0 (s, H, CH -C ' ), (m, 4H, (CH 2 ) 10" and (CH 2 ) 12' ), (s, H, CH - C 4" ), 2. (s, H, CH -C 2' ), (m, H, vinylic CH),.29 (d, J = 1.1 Hz, 1H, vinylic CH),.4 (d, J = 1. Hz, 1H, H 1" ),.47 (d, J = 14.9 Hz, 1H, H ' ),.2 (s, 1H, H 1' ),.8 (dd, J = 14.9 Hz, 11,4 Hz, 1H, H 4' ), 8 (d, J =.1 Hz, 1H, H ), 7.20 (s, 1H, H ), 7. (dd, J = 1. Hz, 11. Hz, 1H, H 2" ), 8.1 (d, J =.1 Hz, 1H, H ) ppm. 1 C- MR (CDCl ) δ 12.8 (CH, CH -C ' ), 12.9 (CH, CH -C 4" ), 14.1 (CH, CH -C 2'' ), 19.2 (CH 2, C 9" or C 11' ), 19. (CH 2, C 9" or C 11' ), 21.7 (CH, CH -C 8" and CH -C 10' ), 29.0 (CH, 2 CH -C 12" and 2 CH -C 14' ),.1 (CH 2, C 10" and C 12' ), 4. (C, C 12" and C 14' ), 9.0 (CH 2, C 11" or C 1' ), 9.4 (CH 2, C 11" or C 1' ), (CH, C ), 12 (CH, C ), 12.7 (CH, C 4' ), (CH, C " or C 8' ), (CH, C " or C 8' ), (CH, C 1" ), (CH, C " ), (CH, C 2" ), 10.0 (C, C 8" or C 10' ), 10.1 (CH, C 1' ), 10. (CH, C ' ), 1.8 (C, C ' ), 17.2 (CH, C " ), 17.8 (CH, C 7' ), (C, C 7" or C 9' ), 17.8 (CH, C ' ), 17.9 (C, C 7" or C 9' ), 19.4 (C, C 4" ), 140. (C, C 2' ), 14.1 (C, C 4 ), (CH, C ), 17.4 (C, C 2 ) ppm. IR (acl, cm -1 ) 2928 (s, C-H), 28 (m, C-H), 1714 (w), 17 (w), 190 (s), 140 (m), 12 (m), 127 (w), 119 (w), 99 (s), 899 (w), 7 (s). MS (EI+) m/z (%) 49 ([M+2] +,11), 48 ([M+1] +, 4), 47 (M +, ), (11), 2 ([M-Me] +, 24), 411 (14), 410 (1), 8 (1). High resolution MS calc for C 40 H ; found UV (MeOH) λ max = 8 nm (ε 49900). 1: 1 H-MR (CDCl ) δ 0.89 (t, 9H, J = 7. Hz, SnCH 2 CH 2 CH 2 CH ), (m, H, SnCH 2 CH 2 CH 2 CH ), 4 (s, H, 2 CH -C 12" ), (m, H, SnCH 2 CH 2 CH 2 CH ), (m, 2H, (CH 2 ) 11" ), -1. (m, H, SnCH 2 CH 2 CH 2 CH ), (m, 2H, (CH 2 ) 10" ), 1.7 (s, H, CH -C 8" ), 0-4 (m, 2H, (CH 2 ) 9" ), 4 (s, H, CH -C 4" ), 2.27 (d, H, J = Hz, CH -C 2' ),.4 (d, J = 2.1 Hz, J 1 H- 119 Sn J 1 H- 117 Sn 2.2 Hz, 1H, H 4' -cis),.04 (d, J = 2.1 Hz, J 1 H- 119 Sn = 1.4 Hz, J 1 H- 117 Sn = Hz, 1H, H 4' -trans),.1 (d, J = 1.2 Hz, 1H, H " ),.22 (d, J = 11.4 Hz, 1H, H " ),.29 (d, J = 1.2 Hz, 1H, H " ),. (br s, 1H, H 1' ),.4 (d, J = 1.4 Hz, 1H, H 1" ), 9 (dd, J =.1 Hz, 1. Hz, 1H, H ), Ren, R. X.-F.; Sakai,.; akanishi, K. J. Am. Chem. Soc. 1997, 119,

12 S (br s, 1H, H ), 7.4 (dd, J = 1.4 Hz, 11.4 Hz, 1H, H 2" ), 8.1 (d, J =.1 Hz, 1H, H ) ppm. 1 C-MR (CDCl ) δ 10. (CH 2, SnCH 2 CH 2 CH 2 CH ), 12.9 (CH, CH - C 4" ), 1.7 (CH, SnCH 2 CH 2 CH 2 CH ), 1. (CH, CH -C 2' ), 19.2 (CH 2, C 10" ), 21.7 (CH, CH -C 8" ), 27. (CH 2, SnCH 2 CH 2 CH 2 CH ), 29.0 (CH, 2 CH -C 12" ), 29.1 (CH 2, SnCH 2 CH 2 CH 2 CH ),.1 (CH 2, C 9" ), 4. (C, C 12 ), 9. (CH 2, C 11" ), (CH, C ), (CH, C ), 12.4 (CH 2, C 4' ), 127. (CH, C 1' ), 128. (CH, C " ), (2xCH, C 1" and C " ), 129. (CH, C 2" ), (C, C 8" ), 17.2 (CH, C " ), 17.7 (C, C 7" ), 19. (C, C 4" ), 1 (C, C 4 ), (C, C 2' ), (CH, C ), 17.8 (C, C 2 ), 1 (C, C ' ) ppm. IR (acl, cm -1 ) 29 (s, C-H), 2924 (s, C-H), 28 (s, C-H), 18 (s), 18 (m), 149 (s), 179 (m), 1288 (w), 120 (w), 11 (w), 107 (w), 1022 (w), 94 (s), 89 (w), 810 (w). MS (ESI) Calc for C 8 H Sn ; found UV (MeOH) λ max = 217 nm (ε 00), 8 nm (ε 2800). A2-E (1) 14 OH 1 A mixture of 14 (2 mg, 0.0 mmol) and 2-iodoethanol (0.04 ml, 0.4 mmol) in CH O 2 (1. ml) was heated at ºC in the dark for 18 h. The reaction mixture was concentrated under reduced pressure. Purification was performed by flash chromatography on silica gel in the dark (SiO 2, 92:8:0.001 CH 2 Cl 2 /MeOH/TFA) affording 24 mg (74%) of A2E (1) 4 as a bright red syrup and 2 mg (%) of iso-a2e. A2-E (1): 1 H-MR (CD OD) δ (s, H, CH -C 12" or CH -C 14' ), (s, H, CH - C 12" or CH -C 14' ), 1.1 (m, 4H, cyclic CH 2 ), 1. (m, 4H, cyclic CH 2 ), 1.7 (s, H, CH -C 8" or CH -C 10' ), 1.7 (s, H, CH -C 8" or CH -C 10' ), (s, H, CH ), 8 (m, 4H, cyclic CH 2 ), 2.1 (s, H, CH ), 2.18 (s, H, CH ),.9 (t, J = 4.8 Hz, 2H, CH 2 CH 2 OH ), 4. (t, J = 4.8 Hz, 2H, CH 2 CH 2 OH),.18 (d, J = Hz, 1H, H " or H " or H 7' or H 8' ),.2 (d, J = 11.4 Hz, 1H, H " or H ' ),.28 (d, J = Hz, 1H, H " or H " or H 7' or H 8' ),.4 (d, J = 1.2 Hz, 1H, H " or H " or H 7' or H 8' ),.42 (d, J = 11.7 Hz, 1H, H " or H ' ),. (d, J = 1.2 Hz, 1H, H " or H " or H 7' or H 8' ),. (d, J = Hz, 1H, H 1" or H ' ),.71 (s, 1H, H 1' ),.77 (d, J = 1. Hz, 1H, H 1" or H ' ), 7.12 (dd, J = Hz, 11.4 Hz, 1H, H 2" or H 4' ), 7.8 (s, 1H, H ), 7.94 (d, J = Hz, 1H, H ), 7.99 (dd, J = 1. Hz, 11.7 Hz, 1H, H 2" or H 4' ), 8. (d, J = Hz, 1H, H ) ppm. 1 C-MR (CD OD) δ 12.9 (CH ), 1. (CH ), (CH ), 20.2 (CH 2 ), 20. (CH 2 ), 21.9 (CH ), 2 (CH ), 29.4 (CH ), (CH 2 ), 4.1 (CH 2 ),.2 (C),.29 (C), 40.8 (CH 2 ), Sakai,.; Decatur, J.; akanishi, K. J. Am. Chem. Soc. 199, 118, Parish, C. A.; Hashimoto, M.; akanishi, K.; Dillon, J.; Sparrow, J. Proc. atl. Acad. Sci. USA 1998, 9,

13 S1 (CH 2 ), 1.1 (CH 2 ), (CH), (CH), 12 (CH), (CH), (CH), 10. (CH), 10.8 (CH), 10.9 (C), 12.1 (CH), 12.2 (C), (CH), 1. (CH), 18.4 (CH), (CH), (C), 19.0 (C), 19.4 (CH), (C), 14.1 (CH), 14.9 (C), (C), 1.4 (C), 14.7 (C) ppm.

14 S14 Br 4 Br H 2 O

15 S1 Br Br Br H 2 O

16 S1 Br 1' OTBS

17 S17 OTBS 1' 7 Br

18 S18 Cl b 1' OTBS H 2 O

19 S19 Br 8 1' OH

20 S20 TMS 1" 1' OTBS 10a H 2 O

21 S21 TMS 1" 1' OH 10c

22 S22 1" 1' 10b OH

23 S2 1" 11a 1' CHO

24 S24 TMS 1" 1' CHO 11b

25 S2 TMS 1" 12a 1' H 2 O

26 S2 1" 12b 1'

27 S27 SnBu 1" 1' SnBu

28 S28 SnBu 1" 1 1' SnBu

29 S29 8" 7" " " 1" 1' ' ' 7' 9' 14 10'

30 S0 8" 7" " " 1" 1' SnBu

31 S1 OH