Chemical and biological evaluation of unusual sugars, α-aculosides, as novel Michael acceptors.

The unusual sugars, α-aculosides, which appear in certain antibiotics and have an α,β-unsaturated ketone structure, were found to be novel and selective Michael acceptors for the thiol function of cysteine residues. A coumarin derivative possessing α-aculoside as a Michael acceptor effectively and irreversibly operated as a fluorescent probe in cells. Furthermore, α-aculosides exhibited cytotoxic activity against several cancer cell lines.

Total synthesis of vineomycin B2.

The first total synthesis of vineomycin B2 (1) has been accomplished. The aglycon segment, a vineomycinone B2 derivative, and the glycon segment, an α-L-acurosyl-L-rhodinose derivative, were prepared via C-glycosylation using an unprotected sugar and powerful chemoselective O-glycosylation using a 2,3-unsaturated sugar, respectively, as the key steps. Furthermore, effective and simultaneous introduction of the two glycon moieties to the aglycon part by concentration-controlled glycosylation led to the total synthesis of 1.