Asymmetric Intermolecular C−H Functionalization of Benzyl Silyl Ethers Mediated by Chiral Auxiliary-Based Aryldiazoacetates and Chiral Dirhodium Catalysts
摘要:
C-H functionalization of benzyl silyl ethers by means of rhodium-catalyzed insertions of aryldiazoacetates can be achieved in a highly diastereoselective and enantioselective manner by judicious choice of chiral catalyst or auxiliary. The dirhodium tetraprolinates such as Rh-2((S)-DOSP)(4) have been widely successful as chiral catalysts in the C-H functionalization chemistry of aryldiazoacetates, but give poor enantioselectivity in the reactions of aryldiazoacetates with benzyl silyl ether derivatives. The use of (S)-lactate as a chiral auxiliary resulted in C-H functionalization with moderately high diastereoselectivity (79-88% de) and enantioselectivity (68-85% ee). The best results (91-95% de, 95-98% ee), however, were achieved using Hashimoto's Rh-2((S)-PTTL)(4) catalyst.
Zur Acylierung von Hydroxy- und Mercapto-carbonsäureestern nach dem Carbodiimid/Acylierungskatalysator-Verfahren
作者:Nagaraj N. Rao、Hermann J. Roth
DOI:10.1002/ardp.19893220903
日期:——
Hydroxycarbonsäureester sind nachdemCarbodiimid/Acylierungskatalysator‐Verfahren leicht und in guten Ausbeuten zugänglich. Die Reaktion kann auch auf Dihydroxy‐ und Mercaptocarbonsäureester ausgedehnt werden. Die aus bestimmten Hydroxycarbonsäureestern erhaltenen Verbindungen sind Hitze‐unbeständig und zersetzen sich leicht unter Freisetzung der Carbonsäure. Bei Einsatz von Enantiomeren als Alkoholkomponente
Asymmetric Intermolecular C−H Functionalization of Benzyl Silyl Ethers Mediated by Chiral Auxiliary-Based Aryldiazoacetates and Chiral Dirhodium Catalysts
作者:Huw M. L. Davies、Simon J. Hedley、Brooks R. Bohall
DOI:10.1021/jo051747g
日期:2005.12.1
C-H functionalization of benzyl silyl ethers by means of rhodium-catalyzed insertions of aryldiazoacetates can be achieved in a highly diastereoselective and enantioselective manner by judicious choice of chiral catalyst or auxiliary. The dirhodium tetraprolinates such as Rh-2((S)-DOSP)(4) have been widely successful as chiral catalysts in the C-H functionalization chemistry of aryldiazoacetates, but give poor enantioselectivity in the reactions of aryldiazoacetates with benzyl silyl ether derivatives. The use of (S)-lactate as a chiral auxiliary resulted in C-H functionalization with moderately high diastereoselectivity (79-88% de) and enantioselectivity (68-85% ee). The best results (91-95% de, 95-98% ee), however, were achieved using Hashimoto's Rh-2((S)-PTTL)(4) catalyst.