Synthesis of 2-amino-5,6-dihydro-4<i>H</i>-1,3-thiazines and related compounds by acid catalyzed cyclization of allylic isothiuronium salts
作者:Noal Cohen、Bruce L. Banner
DOI:10.1002/jhet.5570140502
日期:1977.8.4
Several allylic isothiuronium salts 6 have been shown to yield 4-substituted 2-amino-5,6-dihydro-4H-1,3-thiazines (2; R3 = H) and the 2-phenylimino compound 10 on exposure to trifluoroacetic acid or trifluoroacetic acid-stannic chloride. The overall process constitutes a convenient transformation of readily available ketones or aldehydes 3 into the target hetero-cycles. The scope and limitations of
已显示几种烯丙基异硫脲鎓盐6在暴露于三氟乙酸时会产生4-取代的2-氨基-5,6-二氢-4 H -1,3-噻嗪(2 ; R 3 = H)和2-苯基亚氨基化合物10酸或三氟乙酸-氯化锡。整个过程构成了容易获得的酮或醛3方便地转化为目标杂环的方法。就碳正离子离子中间体(7)讨论了该方法的范围和局限性。鉴于此方法成功生成了咪唑并[2,1- b ] [1,3]噻嗪13(占12%中的93%),其在2-氨基-2-噻唑啉(如14 → 15)或咪唑-[ 2,1- b ]噻唑(如 16 → 17)的合成中的应用未成功。发现2-乙酰基亚氨基衍生物9可用于纯化2-氨基噻嗪。