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