Electronic Supporting Information. Optimisation of a lithium magnesiate for use in the noncryogenic asymmetric deprotonation of prochiral ketones

Transcription

1 Electronic Supporting Information Optimisation of a lithium magnesiate for use in the noncryogenic asymmetric deprotonation of prochiral ketones Javier Francos, Silvia Zaragoza-Calero and Charles T. O Hara* (4-tert-Butylcyclohexen-1-enyloxy)trimethylsilane OOTTMMS tt Bu u 87% yield, Colourless liquid; 1 H NMR (500 MHz, CDCl 3 ) δ (m, 1H), (m, 3H), (m, 2H), (m, 2H), 0.88 (s, 9H), 0.19 (s, 9H). 13 C NMR (125 MHz, CDCl 3 ) δ (C), (CH), 44.0 (CH), 32.1 (C), 30.9 (CH 2 ), 27.4 (CH 3 ), 25.1 (CH 2 ), 24.4 (CH 2 ), 0.34 (CH 3 ). Achiral GC analysis: Chirasil-DEX CB column 30m x 0.25mm x 0.25µm. H 2 carrier gas (45 cmsec -1 ); 90 ºC (0.5 min) to 220 ºC; temperature gradient = 45 ºC min -1 ; t R (1a) = 3.10 min, t R (2a) = 3.17 min. Chiral GC analysis: Chirasil-DEX CB column; H 2 carrier gas (45 cmsec -1 ); º C; temperature gradient = 1.7 ºC min -1 ; t R [(S)-2a] = min, t R [(R)-2a] = min. (4-Propylcyclohexen-1-enyloxy)trimethylsilane OOTTMMS nnppr r 52% yield, Colourless liquid; 1 H NMR (500 MHz, CDCl 3 ) δ (m, 1H), (m, 3H), (m, 2H), (m, 5H), 0.90 (t, 3H, 3 J HH = 7 Hz), 0.18 (s, 9H). 13 C NMR (125 MHz, CDCl 3 ) δ (C), (CH), 38.3 (CH 2 ), 33.1 (CH), 30.4 (CH 2 ), 29.7 (CH 2 ), 29.4 (CH 2 ), 20.3 (CH 2 ), 14.4 (CH 3 ), 0.34 (CH 3 ). Achiral GC analysis: Chirasil-DEX CB column 30m x 0.25mm x 0.25µm. H 2 carrier gas (45 cmsec -1 ); 50 ºC (0.5 min) to 220 ºC; temperature gradient = 45 ºC min -1 ; t R (1b) = 2.89 min, t R (2b) = 2.94 min. Chiral GC analysis: Chirasil-DEX CB column; H 2 carrier gas (45 cmsec -1 ); º C; temperature gradient = 1.7 ºC min -1 ; t R [(S)-2b] = min, t R [(R)-2b] = min. (4-Methylcyclohexen-1-enyloxy)trimethylsilane OOTTMMS Me e 57% yield, Colourless liquid; 1 H NMR (500 MHz, CDCl 3 ) δ (m, 1H), (m, 3H), (m, 2H), (m, 2H), 0.95 (d, 3H, 3 J HH = 6.5 Hz), 0.18 (s, 9H). 13 C NMR (125 MHz, CDCl 3 ) δ (C), (CH), 31.9 (CH 2 ), 30.9 (CH 2 ), 29.3 (CH 2 ), 27.9 (CH), 21.1 (CH 3 ), 0.16 (CH 3 ).

2 Achiral GC analysis: Chirasil-DEX CB column 30m x 0.25mm x 0.25µm. H 2 carrier gas (45 cmsec -1 ); 50 ºC (0.5 min) to 220 ºC; temperature gradient = 45 ºC min -1 ; t R (1c) = 2.36 min, t R (2c) = 2.41 min. Chiral GC analysis: Chirasil-DEX CB column; H 2 carrier gas (45 cmsec -1 ); º C; temperature gradient = 1.7 ºC min -1 ; t R [(S)-2c] = min, t R [(R)-2c] = min. (4-Phenylcyclohexen-1-enyloxy)trimethylsilane OOTTMMS Phh 89% yield, Colourless liquid; 1 H NMR (500 MHz, CDCl 3 ) δ (m, 5H), (m, 1H), (m, 1H), (m, 3H), (m, 3H), 0.27 (s, 9H). 13 C NMR (125 MHz, CDCl 3 ) δ (C), (C), (CH), (CH), (CH), (CH), 40.0 (CH), 31.9 (CH 2 ), 30.2 (2xCH 2 ), 0.42 (CH 3 ). Achiral GC analysis: Chirasil-DEX CB column 30m x 0.25mm x 0.25µm. H 2 carrier gas (45 cmsec -1 ); 50 ºC (0.5 min) to 220 ºC; temperature gradient = 45 ºC min -1 ; t R (1d) = 4.06 min, t R (2d) = 4.12 min. Chiral GC analysis: Chirasil-DEX CB column; H 2 carrier gas (45 cmsec -1 ); ºC; temperature gradient = 1.5 ºC min -1 ; t R [(S)-2d] = min, t R [(R)-2d] = min. (4-iso-Propylcyclohexen-1-enyloxy)trimethylsilane OOTTMMS ii Pr r 75% yield, Colourless liquid; 1 H NMR (500 MHz, CDCl 3 ) δ (m, 1H), (m, 3H), (m, 2H), 1.49 (m, 1H), (m, 2H), 0.90 (d, 3H, 3 J HH = 4.5 Hz), 0.88 (d, 3H, 3 J HH = 4.5 Hz), 0.18 (s, 9H). 13 C NMR (125 MHz, CDCl 3 ) δ (C), (CH), 40.0 (CH), 31.9 (CH), 30.3 (CH 2 ), 27.3 (CH 2 ), 26.5 (CH 2 ), 20.9 (CH 3 ), 19.9 (CH 3 ), 0.31 (CH 3 ). Achiral GC analysis: Chirasil-DEX CB column 30m x 0.25mm x 0.25µm. H 2 carrier gas (45 cmsec -1 ); 50 ºC (0.5 min) to 220 ºC; temperature gradient = 45 ºC min -1 ; t R (1e) = 2.91 min, t R (2e) = 2.96 min. Chiral GC analysis: Chirasil-DEX CB column; H 2 carrier gas (45 cmsec -1 ); º C; temperature gradient = 1.7 ºC min -1 ; t R [(S)-2e] = min, t R [(R)-2e] = min.

3 Table S1. Enantioselective deprotonation of 4-tertbutylcyclohexanone employing different conditions. Base employed T ( C) t(h) G.C yield (%) Enantiomeric ratio (S:R) MgBu H (refluxed in THF) :47 MgBu H (refluxed in THF) + BuLi : 32 2-Li + (Me 3 SiCH 2 ) 2 Mg + 2-H :26 2-Li + (Me 3 SiCH 2 ) 2 Mg + 2-H + LiCl :21

4 NMR chemical shifts of compounds used in D 8 -THF Compound 1 H δ / ppm 7 Li δ / ppm LiBu (t, 2H, 3 J HH = 8.8 Hz), (m, 3H), (m, 2H), (m, 2H) 1.23 (s) LiCH 2 SiMe (s, 2H), 1.65 (s, 9H) 3.39 (s) (CH 2 SiMe 3 ) 2 Mg (s, 4H), (s, 18H) --- LiMg(CH 2 SiMe 3 ) (s, 6H), (s, 27H) 0.38 (s) Figure S1. 1 H NMR of LiBu in D 8-THF. Figure S2. 7 Li NMR of LiBu in D 8-THF. 1 S. E. Baillie, W. Clegg, P. Garcia-Alvarez, E. Hevia, A. R. Kennedy, J. Klett, L. Russo, Organometallics, 2012, 31, 5131.

5 Figure S3. 1 H NMR of LiCH 2SiMe 3 in D 8-THF. Figure S4. 7 Li NMR of LiCH 2SiMe 3 in D 8-THF.

6 Figure S5. 1 H NMR of (CH 2SiMe 3) 2Mg in D 8-THF. Figure S6. 1 H NMR of LiMg(CH 2SiMe 3) 3 in D 8-THF. Compound 1 H δ / ppm CH 3-1 H δ / ppm CH- 1 H δ / ppm Ph- 7 Li δ / ppm 2-H 1.26 (d, 6H, 3 J HH = 6.4 Hz) 3.50 (q, 2H, 3 J HH = 6.4 Hz) (m, 10H) --- Me Me Ph N Li Ph 2-Li (broad singlet, 6H) 3.64 (q, 2H, 3 J HH = 6.8 Hz) (m, 10H) 2.53 (s) (2) 2 Mg THF (d, 12H, 3 J HH = 6.8 Hz) 3.84 (q, 4H, 3 J HH = 6.8 Hz) (m, 20H) A. J. Edwards, S. Hockey, F. S. Mair, P. R. Raithby, R. Snaith, Nigel S. Simpkins, J. Org. Chem., 1993, 58, L. S. Bennie, W. J. Kerr, M. Middleditch, A. J. B. Watson, Chem. Commun., 2011, 47, 2264.

7 Figure S7. 1 H NMR of 2-H in D 8-THF. Figure S8. 1 H NMR of 2-Li in D 8-THF. Figure S9. 7 Li NMR of 4-Li in D 8-THF.

8 Figure S10. 1 H NMR of (2) 2Mg THF in D 8-THF. 1 H δ / ppm 7 Li δ / ppm 2-Li + (CH 2 SiMe 3 ) 2 Mg 2 Li Mg Li SiMe 3 Mg + LiMg(CH 2 SiMe 3)3 SiMe 3 SiMe (m, 1H), (s, 2H), (m, 0.5H), (4 set of signals, 18H), 1.33 (d, 3.7H, 3 J HH = 6.8 Hz), 1.54 (d, 2.6H, 3 J HH = 6.8 Hz), 3.53 (q, 1.14H, 3 J HH = 6.8 Hz), 3.69 (q, 0.90H, 3 J HH = 6.8 Hz), (m, 10H). 13 C δ / ppm , 0.00, 0.22, 5.58, 5.83, 28.94, 29.64, 62.21, 62.59, , , , , , , , Li 2-Li + (CH 2 SiMe 3 ) 2 Mg + excess 2-H Mg SiMe (m, 2H), (2 set of signals, s, 18H; one signal is SiMe 4 ), 1.57 (d, 12H, 3 J HH = 6.8 Hz), 3.70 (q, 4H, 3 J HH = 6.8 Hz), (m, 20H). Corresponding signals for free (4-H) Li + (CH 2 SiMe 3 ) 2 Mg + 4-tert-butylcyclohexanone (m, 0.8H), (m, 0.5H), (4 set of signals, 15H), (major signal)

9 0.931 (2 set of signals, 9H), (m, 3.3H), 1.55 (d, 3.85H, 3 J HH = 6.8 Hz), (signals for 4-tertbutylcyclohexanone), 3.54 (q, 0.46H, 3 J HH = 6.8 Hz), 3.70 (q, 1.16H, 3 J HH = 6.8 Hz), (m, 10H) Figure S11. 1 H NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF. Figure S12. 7 Li NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF.

10 Figure S C NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF. Figure S14. 1 H NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg + 2-H in D 8-THF. Figure S15. 7 Li NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg + 2-H in D 8-THF. Figure S16. 1 H NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg + 4-tert-butylcyclohexanone in D 8-THF.

11 Figure S17. 7 Li NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg + 4-tertbutylcyclohexanone in D 8-THF. Figure S18. DOSY NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF.

12 Figure S19. DOSY NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF; Zoom on CH 3 signals.

13 Figure S20. DOSY NMR of the mixture 2-Li + (CH 2SiMe 3) 2Mg in D 8-THF; Zoom on CH signals.