| 摘要 |
1,155,023. Derivatives of azetidino-thiazolidinemethane carboxylic acids. R. B. WOODWARD. 30 Aug., 1966 [9 Dec., 1965 (2); 13 Jan., 1966], No. 38653/66. Heading C2C. Compounds of the formula wherein Ac represents an aryl group, X represents the disubstituted carbon atom of the thiazolidine ring and R a represents the residue of an alcohol, and isomers and tautomers thereof, may be obtained by reacting an N 1 -unsubstituted 4,4 - disubstituted 3 - acyl - azetidino- [3,2-d]-thiazolidine-2-one of the formula with a diformylmethylene-methane carboxylic acid ester of the formula The reaction is suitably effected in such a manner that decomposition of the olefin is avoided, e.g. at room temperature or by heating to temperatures up to 180‹C., optionally in the presence of a diluent and/or condensing agent and optionally in an inert gas atmosphere and/or under superatmospheric pressure, and the starting materials may be prepared in situ. The products may exist in tautomeric forms and the mixture of isomers obtained from the reaction may be resolved by conventional methods, e.g. fractional crystallization, adsorption chromatography or by forming a mixture of diastereoisomeric salts with optically active salt-forming agents and subsequently breaking down said salts and converting the isolated salts into the free compounds. The specific examples relate to the preparation of 3-tert-butyloxy-carbonyl - α - diformylmethyl - 4,4 - dimethyl - 2 - oxo - 1 - azetidino - [3,2-d] - thiazolidine acetic acid 2,2,2-trichloroethyl ester and the separation of isomers thereof. |
