Quinoxalines. XXVI. Reactions of 2-quinoxalinyl thiocyanate with nucleophiles.
作者:Chihoko IIJIMA、Tomiko KYO
DOI:10.1248/cpb.37.618
日期:——
2-Quinoxalinyl thiocyanate (1) possesses four electrophilic sites, i.e., 2-position, 3-position, sulfur and cyano carbon, to receive nucleophilic attack.Grignard reagents attacked preferentially the sulfur atom to give sulfides (8-12).These sulfides were readily oxidazed to sulfoxides (13-17) with sodium bromite in acetic acid.Hydroxide and ethoxide ions were found to attack preferably the cyano carbon to give thiol (2), while amines (butylamine, piperidine and morpholine) and ethyl cyanoacetate carbanion attacked the carbon at the 2-position to afford the corresponding ipso-substitution products (4-7).
2-喹啉基硫氰酸酯(1)具有四个亲电位点,即2位、3位、硫和氰碳,可以接受亲核攻击。格林纳德试剂优先攻击硫原子,形成了硫化物(8-12)。这些硫化物在醋酸钠溴酸盐的作用下很容易被氧化为亚砜(13-17)。羟基和乙氧基离子优先攻击氰碳,生成硫醇(2),而胺类(丁胺、哌啶和吗啉)和乙基氰乙酸阴离子则攻击2位碳,生成相应的近位取代产物(4-7)。