title: Development of Gold-catalyzed [4+1] and [2+2+1]/[4+2] Annulations between Propiolate Derivatives and Isoxazoles.
abstract: Two new gold-catalyzed annulations of isoxazoles with propiolates have been developed. Most isoxazoles follow an initial O attack on the alkyne to afford a [4+1] annulation product. This process results in a remarkable alkyne cleavage of initial propiolates. Unsubstituted isoxazoles proceed through an N attack step to yield formal [2+2+1]/[4+2] annulation products. These two annulation products arise initially from two seven-membered heterocyclic intermediates, which then lead to products.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Rajkumar Lalji
authors.initials: RL
authors.lastname: Sahani
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu
keywords: annulations; gold; heterocycles; reaction mechanisms; structure elucidation