Fluorinated alcohol-mediated [4 + 3] cycloaddition reaction of indolyl alcohols with cyclopentadiene

Abstract

This paper describes an efficient [4 + 3] cycloaddition reaction of 3-indolylmethanols with cyclopentadiene in hexafluoroisopropanol (HFIP), which is catalyst-free and inexpensive, and offers mild reaction conditions, wide substrate scope and convenient workup. This methodology provides the first catalyst- and additive-free [4 + 3] cycloaddition reactions of indolyl alcohols, offering a green and efficient method for the synthesis of cyclohepta[b]indole derivatives.