Atom-Economic Synthesis of Highly Functionalized Bridged Ring Systems Initiated by Ring Expansion of Indene-1,3-dione

An atom economic procedure for the regioselective synthesis of bridged seven-membered-ring compounds from simple reactants such as ynones and indene-1,3-dione has been developed. This process was realized through the one-pot reactions of ring-expansion of indene-1,3-dione with alkynyl ketones and successive formal [4+2] cycloaddition. The Michael addition reaction is the key for the regioselectivity of the formal [4+2] cycloaddition.

Automated summary

An atom-economic procedure has been developed for the regioselective synthesis of bridged seven-membered-ring compounds from simple reactants. This process involves one-pot reactions of ring-expansion of indene-1,3-dione with alkynyl ketones and successive formal [4+2] cycloaddition, with the Michael addition reaction playing a key role in the regioselectivity of the formal [4+2] cycloaddition.