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Gennari, C.; Ceccarelli, S.; Piarulli, U., Science of Synthesis, (2005) 6, 385.
Tert-butyl propanoate and (+)-menthyl propanoate are enolized by the chiral diazaborolidine reagent 13 and triethylamine in 1:2 toluene/hexane or dichloromethane at −78°C to give the corresponding E(O)-vinyloxyboranes, which add to aldehydes to form anti-aldol products 103 in good enantiomeric excesses (Scheme 45).[17] The same behavior applies to benzyl propanoate, S-benzyl thiopropanoate and S-tert-butyl thiopropanoate, although only a modest enantiomeric excess is obtained in the last case.[116] Interestingly, the re/si face preference of these E(O)-vinyloxyboranes in reactions with aldehydes is opposite to that of the corresponding Z(O)-vinyloxyboranes (see Section 6.1.10.8.5).[116]
Meeeee 88 eeee-Meeeeeeee Meeee Meeeeeee ee e Meeeeeeeeeeeeeeeeeeeeee[88,888]
Mee eeee eeeeeeee eee ee eeeeeeeeeeee eeeeeee ee eee M(M)-eeeeeeeee eeeeeeeeeee ee α-eeeeee-eeeeeeeeeee eeeeeee eeeeee (eeee-eeeee α-eeeee eeeeeee eee eeeee α-eeeeeeeeeeeeeeeeeeeee), eee eeeee eeeeeeee ee eeeee eeeeeeeee eeeeeeeeeeeee eeeeee eeee-eeeee eeeeeeee ee e eeee eeeeeeeeeeee eeeeee.[888,888]
Meeeeeeeeeee Meeeeeeee
eeee-Meeee (8M,8M)-8-Meeeeee-8-eeeeee-8-eeeeeeeeeeeeeeee (888, M8 = Me-Me; M8 = Me); Meeeeee Meeeeeeee:[88]
M,M′-[(8M,8M)-(+)-8,8-Meeeeeeeeeeeee-8,8-eeee]eee[8,8-eee(eeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeee] (888 ee, 8.88 eeee) eee eeeeeeeee ee eeeee MM8Me8 (8 eM) eeeee eeeee ee 8°M eee eeeeeee eeee e 8 M eeee ee MMe8 ee MM8Me8 (8.888 eM, 8.888 eeee). Mee eeeeeee eeee eee eeeeee ee 88°M eee 8 e eee eeeeeeeeeeee ee eeeee. Meeee MM8Me8 (8 eM) eee eeeee eee eee eeeeeee eee eeeeeeeeeeee ee eeeee. Meeee eeeeeee (8 eM) eee eeee eeeee eee eee eeeeeeeee eeeeeee eee eeeeee ee eeeeee eeeeeeee eeeeeeeeeee eee eeee eeeeeee eeee eeeeee (88 eM). Mee eeeeeeeeeee eeee ee eeeeeeeeeee 88 eee eeeeee ee −88°M eee eeeeeee eeee MeMM8e-Me (88 ee, 8.888 eM, 8.88 eeee) eee eeeeeee eee 8 eee. Mee eeeeeeeee eeee eee eeeeeee eeee Me8M (88 ee, 8.888 eM, 8.88 eeee) eee eeeeeee eee 8.8 e ee −88°M. Meeeeeeeeeee (88 ee, 8.888 eM, 8.88 eeee) ee eeeeeee (8.8 eM) eee eeeee eeee 8 eee. Mee eeeeeeee eee eeeeeee ee eeeeeee eee 8.8 e ee −88°M, eee eeeeeeee ee eeeeeeee ee MeMM (8.8 eM) ee −88°M. Mee eeeeeee eee eeeeeee eeee eM 8 eeeeee eeee (8 eM). Meeeeeeeee eeeeeeeee (Me8M) eeeeeeee eee eeee-eeeee eeeeeee (88:8 eeeeee eeeee). Meeeeeee (88%) ee eee M,M-eee(eeeeeeeeeee) eee eeeee eeeeeeeeeeee ee eee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee; eeeee: 88%; 88% ee.
References
[17] | Meeee, M. M.; Mee, M. M., M. Me. Meee. Mee., (8888) 888, 8888. |
[116] | Meeee, M. M.; Mee, M.-M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[140] | Meeee, M. M.; Meee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[141] | Meeee, M. M.; Meee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 88e, 8888.