Practical and Convenient Synthesis of <i>N</i>-Heterocycles: Stereoselective Cyclization of <i>N</i>-Alkenylamides with <i>t</i>-BuOI under Neutral Conditions
[Structure: see text] tert-Butylhypoiodite (t-BuOI) was found to be a powerful reagent for the cyclization of N-alkenylamides leading to a variety of N-heterocycles under extremely mild conditions. When N-alkenylsulfonamides were employed in the reaction, three- to six-membered saturated N-heterocycles were obtained in good to excellent yields with complete stereoselectivity. The method was applicable
A new protocol for the cyclization of N-alkenylamides using chloramine-T and iodine is described. When N-alkenylsulfonamides are treated with chloramine-T and iodine, three- to six-membered N-heterocycles are obtained with complete stereoselectivity. The method is compatible with the cyclization of the allylbenzamide or allylbenzthioamide to afford an oxazoline or thiazoline derivative, respectively. Mechanistic studies indicate that the chloramine-T/I-2 system functions as an effective iodonium species. (c) 2006 Elsevier Ltd. All rights reserved.
Modular Preparation of 5-Halomethyl-2-oxazolines via PhI(OAc)<sub>2</sub>-Promoted Intramolecular Halooxygenation of <i>N</i>-Allylcarboxamides
作者:Gong-Qing Liu、Chun-Hua Yang、Yue-Ming Li
DOI:10.1021/acs.joc.5b01832
日期:2015.11.20
A new method for the construction of oxazoline moiety was detailed. Using (diacetoxyiodo)benzene (PIDA) as the reaction promoter and halotrimethylsilane as the halogen source, intramolecular halooxygenation and halothionation of N-allylcarboxamides/N-allylcarbothioamides proceeded readily, leading : to the corresponding 5-halomethyloxazolines/5-halomethylthiazolines in good to excellent isolated yields. The 5-halomethyl products could be converted to different derivatives via conventional nucleophilic substitution methods. The reactions were carried out using easily available starting materials, and did not need harsh reaction conditions. All these features made this reaction a viable method for the construction of different oxazoline and thiazoline structures.