Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via
6.1.10.9.5 Variation 5: From Vinyloxydiazaborolidines

DOI: 10.1055/sos-SD-006-00296

Gennari, C.; Ceccarelli, S.; Piarulli, U.Science of Synthesis, (20056385.

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] (888ee, 8.88eeee) eee eeeeeeeee ee eeeee MM8Me8 (8eM) eeeee eeeee ee 8°M eee eeeeeee eeee e 8M eeee ee MMe8 ee MM8Me8 (8.888eM, 8.888eeee). Mee eeeeeee eeee eee eeeeee ee 88°M eee 8e eee eeeeeeeeeeee ee eeeee. Meeee MM8Me8 (8eM) eee eeeee eee eee eeeeeee eee eeeeeeeeeeee ee eeeee. Meeee eeeeeee (8eM) eee eeee eeeee eee eee eeeeeeeee eeeeeee eee eeeeee ee eeeeee eeeeeeee eeeeeeeeeee eee eeee eeeeeee eeee eeeeee (88eM). Mee eeeeeeeeeee eeee ee eeeeeeeeeee 88 eee eeeeee ee 88°M eee eeeeeee eeee MeMM8e-Me (88ee, 8.888eM, 8.88eeee) eee eeeeeee eee 8eee. Mee eeeeeeeee eeee eee eeeeeee eeee Me8M (88ee, 8.888eM, 8.88eeee) eee eeeeeee eee 8.8e ee 88°M. Meeeeeeeeeee (88ee, 8.888eM, 8.88eeee) ee eeeeeee (8.8eM) eee eeeee eeee 8eee. Mee eeeeeeee eee eeeeeee ee eeeeeee eee 8.8e ee 88°M, eee eeeeeeee ee eeeeeeee ee MeMM (8.8eM) ee 88°M. Mee eeeeeee eee eeeeeee eeee eM8 eeeeee eeee (8eM). 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


Cookie-Einstellungen