作者:Gerhard Brunner、Laura Eberhard、Jürg Oetiker、Fridtjof Schröder
DOI:10.1021/jo8007397
日期:2008.10.3
In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropyl carbinols.
格氏试剂和二溴甲烷在环境温度下,在乙醚溶剂中有效地环丙酸烯丙基(和某些均烯丙基)醇镁和锂醇化物。锂(均)烯丙基醇盐在较高的Barbier条件下直接与镁和CH2Br2环丙烷化。反应速率取决于(均)烯丙基醇化物的取代方式和取决于锂的抗衡离子,其效果最佳。从α-取代的底物获得良好至优异的顺选择性,这符合交错的Houk模型。在串联反应中,环丙基甲醇是从烯丙基氧基锂或-镁中间体获得的,该中间体是通过共轭醛,酮和酯的烷基化以及烯丙基羧酸盐或乙烯基氧杂环戊烷原位生成的。使用这种方法,