Département de Chimie, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1K 2R1.
J Org Chem. 2012 Dec 21;77(24):11216-26. doi: 10.1021/jo3023507. Epub 2012 Dec 13.
Cyclic hydroxamic acids can undergo a thermal ring contraction after an in situ triflation. High yields of ring-contraction products are obtained with DBU when the migrating carbon is a methylene, while best results are obtained with Et(3)N for the migration of quaternary carbons. In some cases, the regiochemical outcome of the reaction can be controlled by changing the base. This novel thermal rearrangement complements a similar but photochemical rearrangement of N-mesyloxylactams.
环状羟肟酸在原位三氟甲磺酸化后可以发生热环收缩。当迁移的碳原子为亚甲基时，使用 DBU 可以获得高产率的环收缩产物，而对于季碳原子的迁移，最好使用 Et(3)N。在某些情况下，通过改变碱可以控制反应的区域化学结果。这种新的热重排补充了 N-甲磺酰基内酰胺的类似但光化学重排。
