Asymmetric Aminolytic Kinetic Resolution of Racemic Epoxides Using Recyclable Chiral Polymeric Co(III)-Salen Complexes: A Protocol for Total Utilization of Racemic Epoxide in the Synthesis of (<i>R</i>)-Naftopidil and (<i>S</i>)-Propranolol
作者:Manish Kumar、Rukhsana I. Kureshy、Arpan K. Shah、Anjan Das、Noor-ul H. Khan、Sayed H. R. Abdi、Hari C. Bajaj
DOI:10.1021/jo4012656
日期:2013.9.20
Chiral polymeric Co(III) salen complexes with chiral ((R)/(S)-BINOL, diethyl tartrate) and achiral (piper- azine and trigol) linkers with varying stereogenic centers were synthesized for the first time and used as catalysts for aminolytic kinetic resolution (AKR) of a variety of terminal epoxides and glycidyl ethers to get enantio-pure epoxides (ee, 99%) and N-protected beta-amino alcohols (ee, 99%) with quantitative yield in 16 h at RT under optimized reaction conditions. This protocol was also used for the synthesis of two enantiomerically pure drug molecules (R)-Naftopidil (alpha(1)-blocker) and (S)-Propranolol (beta-blocker) as a key step via AKR of single racemic naphthylglycidyl ether with Boc-protected isoproylamine with 100% epoxide utilization at 1 g level. The catalyst 1 was successfully recycled for a number of times.