Synthesis of 1,4-diketones
A visible-light-induced radical coupling reaction of silyl enol ethers with α-bromocarbonyl compounds provides 1,4-dicarbonyls. The reaction was effectively accelerated using an inexpensive organic dye (eosin Y) as a photoredox catalyst.
N. Esumi, K. Suzuki, Y. Nishimoto, M. Yasuda, Org. Lett., 2016, 18, 5704-5707.
In a Co-catalyzed reaction for the construction of 1,4-dicarbonyls, a cascade organocobalt addition/trapping/Kornblum-DeLaMare rearrangement were involved. The reaction offers easy availability of starting materials, wide substrate scope, high functionality tolerance, and operational simplicity.
F. Zhang, P. Du, J. Chen, H. Wang, Q. Luo, X. Wan, Org. Lett., 2014, 16, 1932-1935.
Singly occupied molecular orbital (SOMO) catalysis allows an enantioselective organocatalytic α-enolation of aldehydes. A chiral secondary amine catalyst reacts with aldehydes to form transient enamines that undergo selective one-electron oxidation to generate SOMO-activated electrophilic radical cations which are susceptible to attack by ketone-derived enol silanes.
H.-Y. Jang, J.-B. Hong, D. W. C. MacMillan, J. Am. Chem. Soc., 2007, 129, 7004-7005.