Aminocatalytic Synthesis of Uracil Derivatives Bearing a Bicyclo[2.2.2]octane Scaffold via a Doubly Cycloadditive Reaction Cascade

Abstract

AbstractAminocatalytic synthesis of highly enantiomerically enriched uracil derivatives bearing a bicyclo[2.2.2]octane scaffold is described. The developed strategy utilizes 1,3,6-trimethyl-5-formyluracil and α,β-unsaturated aldehydes as starting materials and has been realized employing various aminocatalytic activation strategies operating in a synergistic manner. The reaction cascade can be described as doubly cycloadditive as it consists of two consecutive Diels–Alder cycloadditions allowing for a facile construction of the bicyclo[2.2.2]octane scaffold. Notably, both steps proceed with dearomatization of the partially aromatic uracil moiety. Excellent stereoselectivity of the reaction cascade is ensured by the use of 2-(diphenylmethyl)pyrrolidine as aminocatalyst.