An asymmetric [4+3]-cyclization reaction of racemic indol-4-ylmethanols and quinone
esters catalyzed by chiral phosphoric acids has been developed. This method provides
efficient access to biologically important [1]benzoxepino[5,4,3-cd]indoles featuring both axial and central chirality in good yields and up to 98% ee,
as essentially single diastereomers, under mild reaction conditions.
Key words
chiral phosphoric acids - [4+3]-cycloaddition - asymmetric catalysis - indoles - quinones
- benzoxepinoindoles