Rhodium-Catalyzed 1,4-Addition of Lithium 2-Furyltriolborates to Unsaturated Ketones and Esters for Enantioselective Synthesis of γ-Oxo-Carboxylic Acids By Oxidation of the Furyl Ring with Ozone
作者:Xiao-Qiang Yu、Tomohiko Shirai、Yasunori Yamamoto、Norio Miyaura
DOI:10.1002/asia.201000589
日期:2011.3.1
Rhodium‐catalyzed 1,4‐addition of lithium 5‐methyl‐2‐furyltriolborate ([ArB(OCH2)3CCH3]Li, Ar=5‐methyl‐2‐furyl) to unsaturated ketones to give β‐furyl ketones was followed by ozonolysis of the furyl ring for enantioselective synthesis of γ‐oxo‐carboxylic acids. [Rh(nbd)2]BF4 (nbd=2,5‐norbornadiene) chelated with 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (binap) or 2,3‐bis(diphenylphosphino)butane
铑催化的5-甲基-2-糠基三硼酸锂([ArB(OCH 2)3 CCH 3 ] Li,Ar = 5-甲基-2-糠基)的1,4加成反应得到β-呋喃酮然后进行呋喃环的臭氧分解,以γ-氧代-羧酸的对映体选择性合成。[Rh(nbd)2 ] BF 4(nbd = 2,5-降冰片二烯)与2,2'-双(二苯基膦基)-1,1'-联萘基(binap)或2,3-双(二苯基膦基)丁烷( Chiraphos)在ee范围为91–99%ee的情况下提供了高收率和高选择性 在碱性二恶烷/水溶液中于30°C加热。在类似条件下,相应的不饱和酯(如巴豆酸甲酯)反应具有很强的抵抗力,但是当使用更多的缺电子巴豆酸苯酯作为底物时,可以得到70%收率和94%ee的1,4-加合物 。