Highly diastereoselective synthesis of spiro[tetrahydrothiophene-3,3′-pyrazol] with an all-carbon quaternary stereocenter via [3 + 2] cascade Michael/Michael cyclization catalyzed by DABCO
作者:Guowei Cai、Shuang Liu、Jiayong Zhang、Yuanyuan Ren、He Wang、Zhiwei Miao
DOI:10.1080/00397911.2016.1174780
日期:2016.5.2
ABSTRACT The diastereoselective formation of spiro[tetrahydro thiophene-3,3′-pyrazol] derivatives has been achieved via a Michael/Michael cyclization reaction. The reaction was performed using trans-ethyl 4-mercapto-2-butenoate 1 with various 4-benzylidene-5-methyl-2-phenylpyrazolones 2 catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) in toluene at 0 °C. The reaction proceeds rapidly and affords
摘要 通过迈克尔/迈克尔环化反应实现了螺[四氢噻吩-3,3'-吡唑]衍生物的非对映选择性形成。使用 4-巯基-2-丁烯酸反式乙酯 1 与各种 4-亚苄基-5-甲基-2-苯基吡唑啉酮 2 进行反应,由 1,4-二氮杂双环 [2.2.2] 辛烷 (DABCO) 在甲苯中于 0 ℃催化℃。反应进行得很快,并以优异的产率和中等至优异的非对映选择性(高达 98% 的产率和 >20:1 dr)得到相应的螺[四氢噻吩-3,3'-吡唑]衍生物。图形概要