Thiourea to Dithiazolopyrimidines: Highly Regio- and Stereoselective Synthetic Routes via Mercaptoacetylative Cyclization
作者:Lal Yadav、Seema Yadav、Vijai Rai
DOI:10.1055/s-2007-990892
日期:2007.12
The Michael addition of 3-imino-1,4,2-dithiazoles to 4-arylidene-1,3-oxathiolan-5-one afforded isolable adducts regio- and diastereoselectively, which underwent mercaptoacetylative annulation of the mercaptopyrimidine ring onto the dithiazole under solvent-free microwave irradiation conditions. Alternatively, similar conjugate addition of [(methylsulfinyl)methyl]isothioureas to 4-arylidene-1,3-oxathiolan-5-one diastereoselectively afforded Michael adducts that underwent mercaptoacetylative ring transformation followed by heterocyclization via deoxygenative demethylation with thionyl chloride to yield the same products, 7-aryl- or 2,7-diaryl-6,7-dihydro-6-mercapto-5H-[1,4,2]dithiazolo[2,3-a]pyrimidin-5-ones, regio- and diastereoselectively.
迈克尔加成反应将3-亚氨基-1,4,2-二噻唑与4-芳基-1,3-氧硫杂环戊烷-5-酮反应,可得到具有区域和立体选择性可分离的加合物,在无溶剂微波辐射条件下,这些加合物与巯基嘧啶环发生巯基乙酰化环化反应,生成二噻唑。或者,类似共轭加成反应将[(甲基亚磺酰基)甲基]异硫脲与4-芳基-1,3-氧硫杂环戊烷-5-酮反应,可得到具有立体选择性的迈克尔加成产物,这些产物发生巯基乙酰化环化反应,然后通过脱氧脱甲基与亚硫酰氯发生异环化反应,生成具有区域和立体选择性的相同产物,即7-芳基或2,7-二芳基-6,7-二氢-6-巯基-5H-[1,4,2]二噻唑并[2,3-a]嘧啶-5-酮。