Development of Gold‐catalyzed [4+1] and [2+2+1]/[4+2] Annulations between Propiolate Derivatives and Isoxazoles. Issue 4 (16th December 2016)

• Record Type: Journal Article
• Authors: Sahani, Rajkumar Lalji; Liu, Rai‐Shung
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 4(2017)
• Page Start: 1026
• Page End: 1030
• Publication Date: 2016-12-16
• Subjects: annulations -- gold -- heterocycles -- reaction mechanisms -- structure elucidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201610665
• Languages: English
• ISSNs: 1433-7851

Abstract

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. Abstract : Plan of attack : Two new gold‐catalyzed annulations of isoxazoles with propiolates have been developed, including [4+1] annulations for most isoxazoles, and formal [2+2+1]/[4+2] annulations for unsubstituted isoxazoles. The different annulations arise initially from different attacks, N or O, by the isoxazoles on the propiolate.