[3, 3]‐Sigmatropic Rearrangement/Allylboration/Cyclization Sequence: Enantioenriched Seven‐Membered‐Ring Carbamates and Ring Contraction to Pyrrolidines. (7th December 2015)

• Record Type: Journal Article
• Authors: Macé, Aurélie; Touchet, Sabrina; Andres, Patricia; Cossío, Fernando; Dorcet, Vincent; Carreaux, François; Carboni, Bertrand
• Is Part Of: Angewandte Chemie. Volume 128:Number 3(2016)
• Page Start: 1037
• Page End: 1041
• Publication Date: 2015-12-07
• Subjects: Allylverbindungen -- Asymmetrische Synthese -- Heterocyclen -- Reaktionsmechanismen -- Umlagerungen; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201509824
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The combination of in situ generated α‐isocyanato allylboronic esters and aldehydes afforded seven‐membered‐ring enecarbamates with high levels of diastereo‐ and enantiocontrol. They were easily converted into diversely substituted 1, 3‐oxazepan‐2‐ones. An unprecedented rearrangement of 5‐acetoxy‐7‐aryl or styryl derivatives led to tetrasubstituted pyrrolidines. A computational study provides evidence on the feasibility of the proposed mechanism of this unusual ring contraction.