Pure Appl. Chem., 2009, Vol. 81, No. 2, pp. 217-226
http://dx.doi.org/10.1351/PAC-CON-08-07-14
Indium-catalyzed Conia-ene reaction for alkaloid synthesis
Abstract:
In(OTf)3-catalyzed cyclization of nitrogen- and oxygen-tethered acetylenic malonic esters provides various five- to seven-membered heterocycles in moderate to excellent yield, and the reaction proceeds with no racemization and complete E-selectivity in the case of chiral and nonterminal alkynes. The synthetic utility is demonstrated by the synthesis of (-)-salinosporamide A, a highly potent 20S proteasome inhibitor, and (+)-neooxazolomycin, a member of the oxazolomycin family of antibiotics.
Keywords
alkaloids; Conia-ene reaction; neooxazolomycin; salinosporamide A; total synthesis.