Synthesis of the N-acetylcysteamine thioester of seco-proansamitocin.

Organic letters (2005-12-31)
Thomas Frenzel, Marco Brünjes, Monika Quitschalle, Andreas Kirschning
ABSTRACT

[structure: see text] The enantioselective total synthesis of the N-acetylcysteamine thioester of seco-proansamitocin, a key biosynthetic intermediate of the highly potent antitumor agent ansamitocin, is described, which twice utilizes the Nagao acetate aldol reaction, as well as an indium-mediated alkynylation of a benzyl bromide followed by carboalumination. The key step is a Heck reaction between two terminal alkenes for merging the two major fragments.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
N-Acetylcysteamine, 95%