Wolff Rearrangement of Oxidatively Generated α‐Oxo Gold Carbenes: An Effective Approach to Silylketenes

• Published in: Angewandte Chemie Vol. 131; no. 16; pp. 5295 - 5299
• Main Authors: Zheng, Yang, Zhang, Junqi, Cheng, Xinpeng, Xu, Xinfang, Zhang, Liming
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 08.04.2019
• Subjects: Alkine; Alkynes; Carbene; Carbenes; Carbonyl compounds; Carbonyls; Carboxylic acids; Chemistry; Gold; Intermediates; Ketene; Nucleophiles; Organic chemistry; Oxides; Umlagerungen
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201814018

Gold‐catalyzed oxidations of alkynes by N‐oxides offer direct access to reactive α‐oxo gold carbene intermediates from benign and readily available alkynes instead of hazardous diazo carbonyl compounds. Despite various versatile synthetic methods developed based on this strategy, one of the hallmarks of α‐oxo carbene/carbenoid chemistry, that is, the Wolff rearrangement, has not been realized in this context. This study discloses the first examples that show the Wolff rearrangement can be readily realized by α‐oxo gold carbenes oxidatively generated from TBS‐terminated alkynes (TBS=tert‐butyldimethylsilyl). The thus‐generated silylketenes can be either isolated pure or subsequently trapped by various internal or external nucleophiles in one pot to afford α‐silylated carboxylic acids, their derivatives, or TBS‐substituted allenes. Die Wolff‐Umlagerung wird erstmals bei der Gold‐katalysierten Oxidation von terminal TBS‐substituierten Alkinen beobachtet. Die Silylgruppe ist für diese Reaktion notwendig, und die erzeugten Silylketene sind stabil und können entweder isoliert oder auf verschiedene Weise abgefangen werden, um γ‐Lactone, α‐silylierte Carbonsäuren und Derivate oder Silylallene zu erhalten.