Base-promoted ring expansion of 3-aminopyrimidine-2-thiones into 1,2,4-triazepine-3-thiones
作者:Anastasia A. Fesenko、Anatoly D. Shutalev
DOI:10.1016/j.tet.2016.03.082
日期:2016.5
A base-promoted ringexpansion of 3-amino-4-hydroxyhexahydropyrimidine-2-thiones into 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones has been developed. Experimental data and DFT calculations showed that the reaction proceeded through fast formation of intermediate acyclic isomers of pyrimidines followed by their slow cyclization into triazepines. The starting hydroxypyrimidines were prepared by
已经开发了3-氨基-4-羟基六氢嘧啶-2-硫酮的碱促进的环扩展成2,4,5,6-四氢-3 H -1,2,4-三氮杂-3-硫酮。实验数据和DFT计算表明,反应是通过快速形成嘧啶的中间体无环异构体,然后缓慢环化为三氮杂s而进行的。通过使α,β-不饱和酮或β-烷氧基酮与HNCS反应,然后用肼处理所获得的β-异硫氰酸根酮来制备起始羟基嘧啶。通过在碱性条件下用H 2 O 2氧化将三氮杂-3-硫酮转化为它们的3-氧代类似物。
Intramolecular, Reductive Cyclization of ?-Ketoisothiocyanates Promoted by Using Samarium Diiodide
作者:Min Seok Cho、In Sang Lee、Sung Ho Kang、Yong Hae Kim
DOI:10.1002/chem.200400676
日期:2005.2.18
A novel samariumdiiodide (SmI2) promoted intramolecular cyclization of beta-ketoisothiocyanate, derived from alpha,beta-unsaturated esters and ammonium thiocyanate led to alpha-hydroxythiolactams and/or thiolactams in high yields. Treatment of beta-ketoisothiocyanate with two equivalents of SmI2 gave a mixture of alpha-hydroxythiolactam and thiolactam. Four equivalents of SmI2 afforded only thiolactam