Phosphine-Catalyzed Intermolecular Dienylation of Alkynoate with para-Quinone Methides

An interesting remote delta-C 1,6-addition and an isomerization cascade reaction for phosphine-catalyzed activated alkynes have been disclosed. The products featuring a functional diene and a 1,1-diaryl methyl motif have been obtained in moderate to good yields (30-86%) by applying para-quinone methides (p-QMs) and delta-substituted alkynoate with tributylphosphine ((PBu3)-Bu-n) catalysis, along with high regioselectivity and stereoselectivity (dr > 20:1). The wide scope of compatible substrates (35 examples), such as indolyl, oxindolyl, ester, and cinnamyl, expand the utility of this methodology. A plausible mechanism and some applications of it have also been presented.

Automated summary

An interesting remote delta-C 1,6-addition and an isomerization cascade reaction for phosphine-catalyzed activated alkynes have been disclosed, yielding products featuring a functional diene and a 1,1-diaryl methyl motif in moderate to good yields (30-86%) with high regioselectivity and stereoselectivity. The methodology shows a wide scope of compatible substrates (35 examples) such as indolyl, oxindolyl, ester, and cinnamyl, expanding its utility. Plausible mechanism and potential applications have also been presented.