Rh-Catalyzed Formation of Dioxolanes from α-Alkyl Diazoesters: Diastereoselective Cycloadditions of Carbonyl Ylides with Selectivity over β-Hydride Elimination

Described here is a diastereoselective Rh-catalyzed method for the preparation of dioxolanes from α-alkyl-α-diazoesters. This represents the first general method for generating carbonyl ylides from α-diazoesters
that possess β-hydrogens, as such diazo compounds typically give rise to alkenes via β-hydride elimination.
Subsequent cycloaddition with aromatic aldehydes gives tetrasubstituted dioxolanes with unusually high
diastereoselectivity. A model is set forth to explain the diastereoselectivity of the cycloaddition.

本文报道了一种非对映选择性铑（Rh）催化方法，可由α-烷基-α-重氮酯制备二氧戊环。这是首个可从带有β-氢的α-重氮酯生成羰基叶立德的通用方法，因为这类重氮化合物通常会通过β-氢消除反应生成烯烃。该羰基叶立德中间体随后与芳香醛发生环加成反应，可得到非对映选择性极高的四取代二氧戊环。本研究还提出了一套反应模型，用以阐释该环加成反应的非对映选择性。