Organocatalyzed Decarboxylative Trichloromethylation of Morita-Baylis-Hillman Adducts in Batch and Continuous Flow
作者:Martin V. Enevoldsen、Jacob Overgaard、Maja S. Pedersen、Anders T. Lindhardt
DOI:10.1002/chem.201704972
日期:2018.1.24
Two protocols for the organocatalyzed decarboxylative trichloromethylation of Morita–Baylis–Hillman (MBH) substrates have been developed. Applying sodium trichloroacetate, as the trichloromethyl anion precursor, in combination with an organocatalyst and acetylated MBH‐alcohols, the desired trichloromethylated products were obtained in good yields at room temperature in batch. The method was next extrapolated
已经开发出两种用于Morita–Baylis–Hillman(MBH)底物的有机催化脱羧三氯甲基化的方案。将三氯乙酸钠作为三氯甲基阴离子的前体,与有机催化剂和乙酰化的MBH-醇结合使用,可以在室温下分批批量获得所需的三氯甲基化产物。接下来将该方法外推到两步连续流方案中,直接从MBH醇开始,与同时用作碱和催化剂的三丁胺结合使用。事实证明,该流动过程优于分批方法,将反应时间从16小时减少到仅20分钟,并且所有调查项目的收率均得到提高。还采用了两个示例来扩大流量,以产生超过10克的两个三氯甲基化靶标。最后,2 PHAL或(DHQD)2 PHAL在反应中诱导手性转移至生成的立体中心,并具有接近90%ee的选择性 。