Direct Alkenylation of Indoles with α‐Oxo Ketene Dithioacetals: Efficient Synthesis of Indole Alkaloids Meridianin Derivatives

Abstract

Let's make 'meri': Metal-free direct alkenylation of indoles was realized by acid-mediated substitution reactions of alpha-oxo ketene dithioacetals with indoles in trifluoroacetic acid/dichloromethane, selectively affording beta-indolyl mono- and disubstituted alpha,beta-unsaturated carbonyl compounds (see scheme). Condensation of the indolyl/ketene monothioacetals and guanidine nitrate efficiently produced meridianin derivatives.