Pyridinium 1,4-zwitterionic thiolates as a useful class of sulfur-containing synthons: application to the synthesis of 2,5-dihydro-1,4,5-thiadiazepines
A novel [4+3] cascade cyclization reaction of pyridinium 1,4-zwitterionic thiolates with azoalkenes derived from α-halo hydrazones in situ has been developed. This reaction was found to allow expedient access to an array of 2,5-dihydro-1,4,5-thiadiazepines. Libraries of highly functionalized sulfoxide and sulfone analogues of 2,5-dihydro-1,4,5-thiadiazepines were also obtained via selective oxidation
An unprecedented [4+3] cycloaddition of in situ generated azoalkenes with C,N-cyclicazomethineimines has been developed without the use of any catalyst, providing an efficient and mild approach to synthesise highly functionalized 1,2,4,5-tetrazepine derivatives in high yields (76-92%).
Construction of 2,3,4,5-tetrahydro-1,2,4-triazines via [4 + 2] cycloaddition of α-halogeno hydrazones to imines
作者:Hong-Wu Zhao、Hai-Liang Pang、Yu-Di Zhao、Yue-Yang Liu、Li-Jiao Zhao、Xiao-Qin Chen、Xiu-Qing Song、Ning-Ning Feng、Juan Du
DOI:10.1039/c6ra27767e
日期:——
In the presence of sodium carbonate, the [4 + 2] cycloaddition of α-halogeno hydrazones to imines proceeded readily, and furnished 2,3,4,5-tetrahydro-1,2,4-triazines in moderate to high chemical yields.
In the presence of sodium carbonate, the [4+3] cycloadditions of α‐halogeno hydrazones with nitrones were performed efficiently, and affording 2,3,4,7‐tetrahydro‐1,2,4,5‐oxatriazepines in moderate to high yields.