3,4-Dibromotetrahydro-lambda~6-thiophene 1,1-Dioxide in S,N-Tandem Heterocyclizations.Synthesis of Tetrahydrothieno-thiazolopyrimidines

摘要

Pyrimidine derivatives possess important pharmacological properties[1].Among these,the most prominent are such naturally occurring alkaloids as batzella-dines[2],ptilomycalins[3],saxitoxins[4],and luoto-nins[5];their molecules include five-membered saturated rings fused to a pyrimidine base.We previously showed[6]that 2,3-dibromopropyl sulfones readily undergo heterocyclization with 2-thiouracils.While-continuing studies on tandem heterocyclizations,we have synthesized tetrahydrothienothiazolopyrimidine derivatives via S,N-tandem alkylation of 2-thiouracils Ia and Ib with 3,4-dibromotetrahydro-lambda~6-thiophene 1,1-dioxide.The reactions were carried out in ethanol at room temperature,the reactant ratio dibromosulfo-lane-2-thiouracil I-potassium hydroxide being 1:2:4;the reactions were complete in 8 h,and the yields of products IIa and IIb were 78-80%.