A Lewis Acid-Catalyzed Diastereoselective Synthesis of Functionalized 2-Diazo-1,5-dicarbonyl Compounds

A diverse array of 2-diazo-1,5-dicarbonyl compounds were formed by the Lewis acid-catalyzed reaction of enoxysilanes with beta-hydroxy-alpha-diazo carbonyls. This reaction proceeds via the Zn(OTf)(2)-catalyzed dehydroxylation of the beta-hydroxy-alpha-diazo carbonyl to form a vinyl diazonium ion intermediate that is intercepted by the enoxysilane nucleophile to give diazo-containing scaffolds with increased molecular complexity. The reaction appears to be general, and a variety of functional groups, including common protecting groups, are well tolerated. The 2-diazo-1,5-dicarbonyl products are formed in yields of up to 99% with diastereoselectivity up to >20:1.