2-(Acylmethylene) hexahydropyrimidines (7) have been converted into the corresponding benzoyl isothiocyanate adducts (8), treatment of which with sulphuryl chloride gave the 3-chloroisothiazolo[2,3-a]pyrimidine (10) instead of the expected 3-acyl compound (9). Oxidation of the adduct (8c) by bromine gave the isothiazolo[2,3-a]-pyrimidine (9c) in low yield; this failed to undergo base-catalysed fragmentation
2-(酰基亚甲基)六氢
嘧啶(7)已转化为相应的
苯甲酰基异硫氰酸酯加合物(8),用
硫酰氯处理可得到
3-氯异噻唑并[2,3- a ]
嘧啶(10),而不是预期的3-酰基化合物(9)。
溴将加合物(8c)氧化后,
异噻唑并[2,3- a ]-
嘧啶(9c)的收率低;这未能进行碱催化的腈裂解(13c)。最后,通过与1-甲基-2-甲
硫基-1,4,5,6-四氢
嘧啶(12)缩合,由苯甲酰基-和2-巯基甲基-
氰化物(11)制备α-酰基-α-
氰基亚甲基六氢
嘧啶(13)。 )。