Enantioselective Phosphine‐Catalyzed Formal [4+4] Annulation of α, β‐Unsaturated Imines and Allene Ketones: Construction of Eight‐Membered Rings. (10th October 2017)

• Record Type: Journal Article
• Authors: Ni, Huanzhen; Tang, Xiaodong; Zheng, Wenrui; Yao, Weijun; Ullah, Nisar; Lu, Yixin
• Is Part Of: Angewandte Chemie. Volume 129:Number 45(2017)
• Page Start: 14410
• Page End: 14414
• Publication Date: 2017-10-10
• Subjects: Anellierungen -- Heterocyclen -- Organokatalyse -- Phosphane -- Synthesemethoden; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201707183
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The first highly enantioselective phosphine‐catalyzed formal [4+4] annulation has been developed. In the presence of amino‐acid‐derived phosphines, the unprecedented [4+4] annulations between benzofuran/indole‐derived α, β‐unsaturated imines and allene ketones proceeded smoothly, thus affording azocines, bearing either a benzofuran or an indole moiety, in excellent yields and with nearly perfect enantioselectivities (≥98 % ee in most cases). This work marks the first efficient asymmetric construction of optically enriched eight‐membered rings by phosphine catalysis.