1.
Chirality
; 20(7): 856-62, 2008 Jul.
Artigo
em Inglês
| MEDLINE
| ID: mdl-18381733
RESUMO
The present article describes the asymmetric synthesis of (R)-bambuterol hydrochloride based on 1-(3,5-dihydroxyphenyl)ethanone as starting material, which was esterified by dimethylcarbamic chloride, and brominated by copper (II) bromide. Then the carbonyl group was reduced efficiently using (-)-B-chlorodiisopinocamphenylborane [(-)-DIP-chloridetrade mark] as an asymmetrical reducing agent. Followed by epoxide ring closure with NaOH and ring expansion with tert-butylamine led to the desired product (R)-bambuterol with e.e. up to 99%. The optical properties and absolute configuration of (R)-bambuterol hydrochloride were further investigated using circular dichroism spectroscopy and X-ray single crystal analysis.