Catalytic asymmetric synthesis of descurainin via 1,3-dipolar cycloaddition of a carbonyl ylide using Rh 2( R-TCPTTL) 4

Abstract

A catalytic asymmetric synthesis of descurainin has been achieved by incorporating an enantioselective 1,3-dipolar cycloaddition, a stereoselective alkene hydrogenation, an oxidation with Fremy’s salt and a regioselective demethylation with NbCl 5 as the key step. The 1,3-dipolar cycloaddition of a carbonyl ylide derived from tert-butyl 2-diazo-5-formyl-3-oxopetanoate with 4-hydroxy-3-methoxyphenylacetylene in the presence of dirhodium(II) tetrakis[ N-tetrachlorophthaloyl-( R)- tert-leucinate], Rh 2( R-TCPTTL) 4, provided an 8-oxabicyclo[3.2.1]octane skeleton in 95% ee.