作者:Merritt B. Andrus、Michael A. Christiansen、Erik J. Hicken、Morgan J. Gainer、D. Karl Bedke、Kaid C. Harper、Shawn R. Mikkelson、Daniel S. Dodson、David T. Harris
DOI:10.1021/ol702197r
日期:2007.11.1
2-Acylimidazoles are alkylated under phase-transfer conditions with cinchonidinium catalysts at -40 degrees C with allyl and benzyl electrophiles in high yield with excellent enantioselectivity (79 to >99% ee). The acylimidazole substrates are made in three steps from bromoacetic acid via the N-acylmorpholine adduct. The catalyst is made in high purity allowing for S-product formation (6-20 h) under
在2-辛基吡啶鎓催化剂的相转移条件下,将2-酰基咪唑与烯丙基和苄基亲电子试剂在-40℃下以高收率和优异的对映选择性(79至> 99%ee)烷基化。酰基咪唑底物由溴乙酸经N-酰基吗啉加合物分三步制备。该催化剂以高纯度制备,可在温和条件下形成S产物(6-20小时),这与离子对机理相符。使用三氟甲磺酸甲酯和甲醇钠,经由二甲基酰基咪唑鎓中间体容易地将产物转化为有用的酯产物,而没有外消旋作用。该过程是有效的,直接的,并且适合于通过烯醇化中间体进行的其他亲电试剂和转化。