Umpolung Morita-Baylis-Hilman C-H functionalization of unsaturated ketones via in situ formation of electrophilic enolonium species

The Morita-Baylis-Hillman reaction is a unique reaction for C-H functionalization of the α-position of activated α,β unsaturated ketones.¹ The classical reaction involves formation of a nucleophilic enolate through the reversible conjugate addition of an amine with subsequent reaction with an aldehyde (See Scheme). We have explored and developed a novel concept that allows the umpolung of the in situ formed enolate into an electrophilic enolonium species by the action of hypervalent iodine reagents (See Scheme for proposed mechanism).² This new concept has been utilized in several C-O bond forming reactions including α-tosylation, -triflation, and -acetoxylation).

1) Morita, K.-i.; Suzuki, Z.; Hirose, H. Chem. Soc.Japan 1968, 41, 2815.

2) Arava, S., Kumar, J. N., Maksymenko, S., Iron, M. A., Parida, K. N., Fristrup, P., & Szpilman, A. M. Chem. 2017 129, 2643-2647.