Ring closure reactions of pyrido[2,3-<i>d</i>]pyrimidines to pyrano[2′,3′:4,5]- and oxazolo[5′,4′:4,5]pyrido[2,3-<i>d</i>]pyrimidines
作者:Dang Van Tinh、Wolfgang Stadlbauer
DOI:10.1002/jhet.5570450517
日期:2008.9
zinc in the presence of carboxylic acids/anhydrides gave 2-alkyloxazolo[5′,4′:4,5]pyrido[2,3-d]pyrimidines 4, which were ring-opened to 6-aminopyrido[2,3-d]pyrimidines 5, 6 and 7. Cyclization of 6-aminopyrido[2,3-d]pyrimidines 6 with benzoylchlorides 8 gave 2-aryloxazolo[5′,4′:4,5]pyrido[2,3-d]pyrimidines 9. Reaction conditions for the cyclization have been studied by differential scanning calorimetry
5-羟基-吡啶并[2,3- d ]嘧啶1与丙二酸酯的环缩合反应得到吡喃并[2',3':4,5]-吡啶并[2,3- d ]嘧啶2。硝化1并在羧酸/酸酐存在下用锌还原得到2-烷基恶唑并[5',4':4,5]吡啶[2,3- d ]嘧啶4,将其开环成6-氨基吡啶[2,3- d ]嘧啶5、6和7。6-氨基吡啶并[2,3- d ]嘧啶6与苯甲酰氯8的环化反应生成2-芳基恶唑并[5',4':4,5]吡啶并[2,3- d ]嘧啶9。通过差示扫描量热法(DSC)已经研究了用于环化的反应条件。