An unusual stereochemical outcome of radical cyclization: synthesis of (+)-biotin

Copper(I)‐Promoted Synthesis of Highly Substituted and Functionalized Tetrahydrothiophenes

“…Radical reactions have been used extensively for the synthesis of substituted five‐membered carbocycles and N ‐ and O ‐heterocycles, and the stereochemical aspects of such reactions have been thoroughly investigated. A light‐induced intramolecular radical cyclization and a few reductive radical cyclizations using Bu 3 SnH have been reported for the synthesis of THTs. A Bu 3 SnH/AIBN‐mediated radical cyclization of 2‐bromoaryl allyl sulfide to give the dihydrobenzo[ b ]thiophene is also known .…”

Muscarine, imidazole, oxazole and thiazole alkaloids

“…Recently, several synthetic strategies for (+)-biotin and its derivatives have been developed. [117][118][119][120] Phorboxazoles A 225a and B 225b (the epimer at C13), originally isolated from the Indian Ocean sponge Phorbas sp., have been found to exhibit significant cytostatic activity at the S phase with a mean GI 50 <1.58 nM against a broad spectrum of human cancer cell lines. This extraordinary cytotoxic activity and complex molecular structures have made them fascinating synthetic targets.…”

Total Synthesis of Laucysteinamide A, a Monomeric Congener of Somocystinamide A

“…Accordingly, olefin cross metathesis substrates 6 and 7 were prepared. The olefin 7 was synthesized from l -cysteine in five steps as reported with orthogonal protection by the phenyl thiazolidine and N-Boc. ,, Commercially available 11-bromo-1-undecene was homologated by a malonate ester and subsequently decarboxylated to 5 (see Supporting Information) and coupled with methylamine to afford the amide 6 . , Coupling of 6 and 7 by Hoveyda–Grubbs II catalyst was achieved with an excellent yield. The resulting long-chain amide 8 was deprotected via Birch reduction to afford a thiol, which was then acetylated, forming thioester 9 .…”