ISSN:
1573-1111
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The gas-solid halogenation and hydrohalogenation using microcrystalline cyclodextrin complexes are found to be efficient for production of the optical active halides of ethyltrans-cinnamate in moderate optical yields: On exposure to HBr at 20°C for 15–20 hr, the cinnamate in solid α- and β-cyclodextrin complexes yields ethyl R-(+)-3-bromo-3-phenylpropanoate in 46% e.e., and S-(−)-enantiomer in 31% e.e., respectively. No addition nor substitution products are obtained with HC1 vapor at 0–50°C for 15–65 hr. Bromination of the β-cyclodextrin complex results in the formation of optical active ethylerythro-2,3-dibromo-3-phenylpropanoate, while chlorination gives the optical active mixture oftrans andcis addition products, ethylerythro- andthreo-2,3-dichloro-3-phenylpropanoates in 60–80% yields. Mechanism of chiral induction in the present gas-solid reaction has been proposed on the basis of the crystal structure of the complex.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00662253
Permalink