Synthesis of Highly Substituted Furans by a Cascade of Formal anti-Carbopalladation/Hydroxylation and Elimination.

Highly substituted furans are generated by a cascade of formal anti-carbopalladation, attack of a nucleophilic hydroxy group, and aromatization by elimination of the emerging dihydrofuran derivative. Mono-, di-, and trisubstituted furans were obtained in good to excellent yields. When we attempted to access tetrasubstituted furan derivatives, an additional rearrangement was observed that resulted in the formation of chromenes. Follow-up chemistry shows the utility of TMS as a protecting group for the alkyne moiety.