Welwistatin support studies: expansion and limitation of aryllead(IV) coupling reactions.
Recent support studies on the total synthesis of the welwistatin system are described. The target step involves lead-mediated arylation of sterically demanding aryl groups and carbon acid coupling partners in order to establish the highly congested tetracyclic core structure. Type 7 beta-ketoesters and beta-ketonitriles were successfully arylated with a variety of ortho- and meta-substituted aryllead compounds generated by a halogen-boron-lead exchange sequence. The enolates of compounds 15, 19, and 25, each bearing all-carbon quaternary centers adjacent to the arylation site, failed to couple.
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
Jibo
J
Xia
Lauren E
LE
Brown
Joseph P
JP
Konopelski
D007854:Lead / Q000737:chemistry*; D015394:Molecular Structure
D007854:Lead