Phosphine‐Catalyzed Annulations of 4,4‐Dicyano‐2‐Methylenebut‐3‐enoates with Maleimides and Maleic Anhydride

• DOI: 10.1002/anie.201406100
• Publication Date: 2014-08-19T20:24:44Z
• Authors: Xiao‐Nan Zhang; Gen‐Qiang Chen; Xiang‐Ying Tang; Yin Wei; Min Shi
• Keywords: Synthon; Maleic anhydride; Annulation

Abstract A novel phosphine‐catalyzed [4+1] annulation of maleimides with 4,4‐dicyano‐2‐methylenebut‐3‐enoates has been developed to afford spirocyclic products, and the serves as C 1 synthons. Moreover, a formal [3+2] between maleic anhydride also achieved, behaved 3 synthon in reaction, thus efficiently affording functionalized cyclopentenones. stable phosphinium‐containing zwitterionic compound is key reactive intermediate both annulations was successfully isolated. Plausible mechanisms have proposed on basis control experiments deuterium‐labeling experiments.