研究了以1-芳基-2-氟乙醇为亲核试剂对4-氯喹唑啉和6-溴-4-氯噻吩并[2,3- d ]嘧啶的亲核芳香取代反应,重点是结合环境可接受的溶剂使用碳酸盐碱。转化率取决于溶剂性质,亲核试剂的酸度和碱的性质。通过使用乙腈作为反应介质并且以K 2 CO 3为碱,可以将2,2,2-三氟-,2,2-二氟-和2-氟-1-苯基乙醇有效地偶联到4-氯嘧啶上。或者,使用Cs 2 CO 3,可以缩短这些底物的反应时间,并且非氟化醇的偶联也进行得很好。还发现叔丁醇是氟代醇转化中合适的反应介质。对4-烷氧基嘧啶的水解稳定性的测试表明,氟化和非氟化衍生物在酸性条件下均不稳定,而在碱性介质中,氟烷氧基衍生物比其非氟化衍生物更稳定。
The effects of both steric and electronic properties of ketones on the selectivity in asymmetric transfer hydrogenation have been studied with aryl alkyl/fluoroalkyl ketones using four ruthenium based catalysts and two different media. The 1-arylethanones, 1-aryl-2-fluoroethanones and 2,2-difluoroacetophenones could be reduced with medium to high ee (86–99%), while the 1-aryl-2,2,2-trifluoroethanones
Nucleophilic difluoromethylation and difluoromethylenation of aldehydes and ketones using diethyl difluoromethylphosphonate
作者:Petr Beier、Anastasia V. Alexandrova、Mikhail Zibinsky、G.K. Surya Prakash
DOI:10.1016/j.tet.2008.10.006
日期:2008.12
New methodology for difluoromethylation and difluoromethylenation of aldehydes and ketones based on nucleophilic fluorination using diethyl difluoromethylphosphonate (1) was developed.