Cycloaromatization ofα-oxoketene dithioacetals with lithioacetonitrile and lithiopropionitrile: a facile route to substituted and annelated pyridines
作者:Arun K. upta、Hiriyakkanavar Ila、Hiriyakkanavar Junjappa
DOI:10.1016/s0040-4020(01)82036-6
日期:1990.1
1,3-MeS shift in the presence of phosphoric acid to afford a variety of substituted and annelated 2,6-bis(methylthio)pyridines 3 and 4 respectively in good yields. Cyclization of 2 in the presence of bromine and acetic acid yielded the corresponding 2-bromo-6- methylthio-4,5-substituted and annelated pyridines 9 in good yields. The bis(methylthio) groups in 3 could either be removed with Raney Nickel
通过将1,2-硫代乙腈或硫代丙腈加到α-氧杂环丁烯二硫缩醛1上而得到的烯醇缩醛2在磷酸存在下发生分子内Ritter反应,伴随着1,3-MeS的转变,从而得到各种取代的和退火的2, 6-双(甲硫基)吡啶3和4分别具有良好的收率。在溴和乙酸的存在下将2环化,以良好的产率得到相应的2-溴-6-甲硫基-4,5-取代的和退火的吡啶9。3中的双(甲硫基)基团可以用阮内镍(Raney Nickel)除去或在三苯基膦-氯化镍氯化物络合物存在下用甲基取代,从而以高收率得到相应的脱硫(8)或甲基化(15)吡啶。尝试将烯醇缩醛2a环化,