Cyclisierungsreaktionen β,γ‐ungesättigter Kohlensäurederivate. IX. Regiochemie der elektrophilen Cyclofunktionalisierung β,γ‐ungesättigter Carbamidsäureester mit Brom – Synthese von Oxazolidin‐2‐onen und Tetrahydro‐2H‐1,3‐oxazin‐2‐onen

• Published in: Journal für Praktische Chemie
• Main Authors: Mühlstädt, M., Olk, B., Widera, R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1986
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1002/prac.19863280204; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fprac.19863280204; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fprac.19863280204; https://onlinelibrary.wiley.com/doi/pdf/10.1002/prac.19863280204

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. IX. Regiochemistry of Electrophilic Cyclofunctionalization of β,γ‐Unsaturated Carbamic Acid Esters with Bromine – Synthesis of Oxazolidine‐2‐ones and Tetrahydro‐2H‐1,3‐oxazine‐2‐ones N,N‐Disubstituted β,γ‐unsaturated urethanes ( 1 ) and bromine react in methylene chloride at room temperature. The crotyl urethanes ( 1a – 1c and 1e ) and bromine give mixtures of corresponding saturated urethanes (dibromine adducts) ( 2a – 2c and 2e ), the oxazolidine‐2‐ones ( 3a – 3c and 3e ), and the tetrahydro‐2H‐1,3‐oxazine‐2‐ones ( 4a – 4c and 4e ). The reaction of γ,γ‐dimethylallyl urethanes ( 1f – 1h ) with bromine gives similar results. A useful synthetic route to N‐substituted tetrahydro‐2H‐1,3‐oxazine‐2‐ones ( 4l – 4q ) is demonstrated by the reaction of cinnamyl urethanes ( 1l – 1q ) with bromine.