Rh(II)/Mg(OtBu)2-Catalyzed Tandem One-Pot Synthesis of 1,4-Oxazepines and 1,4-Oxazines from N-Sulfonyl-1,2,3-triazoles and Glycidols

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• 作者：Young Ok Ko ; Hyun Ji Jeon ; Da Jung Jung ; U Bin Kim ; Sang-gi Lee
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：December 16, 2016
• 年：2016
• 卷：18
• 期：24
• 页码：6432-6435
• 全文大小：399K
• ISSN：1523-7052

文摘

A novel, one-pot route for the synthesis of nonaromatic ring-fused 1,4-oxazepines and 1,4-oxazines has been developed. The reaction features a sequential rhodium(II)-catalyzed reaction of N-sulfonyl-1,2,3-triazoles with glycidols, followed by a regioselective Lewis acid Mg(O^tBu)₂-catalyzed intramolecular ring-opening reaction. It has been found that the regioselectivity in the epoxide ring-opening was largely determined by the substituents on the glycidols. Thus, substituted glycidols (R² ≠ H) afforded seven-membered oxazepine derivatives selectively, while unsubstituted glycidols (R² = H) afforded six-membered oxazine derivatives. Plausible reaction pathways are elucidated and supported by experiments with several glycidols bearing different substituents around the epoxide functionality.