Syntheses of Highly Functionalized Spirocyclohexenes by Formal [4+2] Annulation of Arylidene Azlactones with Allenoates. Issue 8 (10th June 2018)

• Record Type: Journal Article
• Authors: Eitzinger, Andreas; Zielke, Katharina; Widhalm, Michael; Robiette, Raphaël; Waser, Mario
• Is Part Of: Asian journal of organic chemistry. Volume 7:Issue 8(2018)
• Page Start: 1620
• Page End: 1625
• Publication Date: 2018-06-10
• Subjects: allenes -- annulation -- density functional calculations -- diastereoselectivity -- phosphines; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.201800275
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: A straightforward phosphine‐catalyzed formal [4+2] annulation between α‐branched allenoates and arylidene azlactones has been developed to access highly functionalized spirocyclohexenes. This cyclization favors the γ‐addition of the phosphine‐activated allenoates over a β′‐addition pathway. Detailed computational studies support the proposed mechanism and provide a reasonable explanation for the observed regioselectivity and the noted effect of the catalyst. Abstract : A pinch of PBu3 : A phosphine‐catalyzed [4+2] annulation between α‐branched allenoates and arylidene azlactones has been developed to access highly functionalized spirocyclohexenes. EWG=electron‐withdrawing group.