Asymmetric induction in [2+2]cycloaddition of chlorosulfonyl isocyanate to 1,2-O-isopropylidene-3-O-vinyl-glycofuranoses
摘要:
The asymmetric [2+2]cycloaddition of chlorosulfonyl isocyanate to 1,2-O-isopropylidene-3-O-vinylglycofuranoses is presented. Bulky substituent at the C-4 carbon atom promotes excellent stereoselectivity affording (R) configuration at the C-4' carbon atom of the azetidinone ring. Intramolecular cyclization in compounds 9 or 12 provides diastereomeric cephem 20 and 21.
Asymmetric induction in [2+2]cycloaddition of chlorosulfonyl isocyanate to 1,2-O-isopropylidene-3-O-vinyl-glycofuranoses
摘要:
The asymmetric [2+2]cycloaddition of chlorosulfonyl isocyanate to 1,2-O-isopropylidene-3-O-vinylglycofuranoses is presented. Bulky substituent at the C-4 carbon atom promotes excellent stereoselectivity affording (R) configuration at the C-4' carbon atom of the azetidinone ring. Intramolecular cyclization in compounds 9 or 12 provides diastereomeric cephem 20 and 21.