Tandem Transesterification and Intramolecular Cycloaddition of α-Methoxycarbonylnitrones with Chiral Acyclic Allyl Alcohols: Systematic Studies on the Factors Affecting Diastereofacial Selectivity of the Cycloaddition

摘要: Factors affecting the stereochemical course of intramolecular cycloaddition intermediary α-allyloxycarbonylnitrone resulting from transesterification α-methoxycarbonylnitrones 1a−d with chiral allyl alcohols 5 or 6 were investigated systematically. It was found that factors diastereofacial selection are highly dependent on geometries alcohols. In cases where primary secondary (Z)-allyl used, A(1,3)-strain arising chiralities in (Z)-nitrone transition states cycloaddtion is most important factor. contrast, case reaction using nitrones 1c,d and (E)-allyl alcohols, steric interaction between N-substituent trans substituent olefin moiety intermediate dominant. These aspects applied to geometry-differentiated a mixture (E)-5 (Z)-5. As typical example, treatment bulky 1b 1:1 (Z)-5 pr...