Asymmetric Functionalization of Chromium Carbene-Derived Optically Active 4,4-Disubstituted Butenolides
摘要:
Optically active 4,4-disubstituted butenolides were readily prepared by photolysis of chromium alkoxycarbene complexes with optically active ene carbamates, followed by Baeyer-Villiger oxidation/oxazolidinone elimination. These butenolides underwent clean 1,3-dipolar cycloaddition reactions with cyclic nitrones exclusively from the more hindered face of the butenolide. Azomethine ylides were considerably less stereoselective. Conjugate addition reactions also occurred from the more hindered face, while cis hydroxylation occurred from the opposite face.
Asymmetric Functionalization of Chromium Carbene-Derived Optically Active 4,4-Disubstituted Butenolides
摘要:
Optically active 4,4-disubstituted butenolides were readily prepared by photolysis of chromium alkoxycarbene complexes with optically active ene carbamates, followed by Baeyer-Villiger oxidation/oxazolidinone elimination. These butenolides underwent clean 1,3-dipolar cycloaddition reactions with cyclic nitrones exclusively from the more hindered face of the butenolide. Azomethine ylides were considerably less stereoselective. Conjugate addition reactions also occurred from the more hindered face, while cis hydroxylation occurred from the opposite face.
Asymmetric Functionalization of Chromium Carbene-Derived Optically Active 4,4-Disubstituted Butenolides
作者:A. D. Reed、Louis S. Hegedus
DOI:10.1021/jo00117a034
日期:1995.6
Optically active 4,4-disubstituted butenolides were readily prepared by photolysis of chromium alkoxycarbene complexes with optically active ene carbamates, followed by Baeyer-Villiger oxidation/oxazolidinone elimination. These butenolides underwent clean 1,3-dipolar cycloaddition reactions with cyclic nitrones exclusively from the more hindered face of the butenolide. Azomethine ylides were considerably less stereoselective. Conjugate addition reactions also occurred from the more hindered face, while cis hydroxylation occurred from the opposite face.