Process of producing 6-styryl-5,6-dihydro-alpha-pyrone compounds

Abstract

Abstract 6-STYRL - 5,6 - DIHYDRO - A - PYRONE COMPOUND SUCH AS KAWAIN AND METHYSTICIN ARE PRODUCED BY CONDENSING $-HALOGENO-B-ALKOXY CROTONIC ACID ESTERS WITH CINNAMIC ALDEHYDE OR ITS ACETAL OR ALKOXY- OR METHYLENEDIOXYSUBSTITUTED CINNAMIC ALDEHYDE OR ACETAL IN THE PRESENCE OF METALLIC ZINC. WHEN DECOMPOSING THE RESULTING ORGANO-ZINC SALT BY A TREATMENT WITH A DILUTE MINERAL AIC, PREFERABLY 10% HYDROCHLORIC ACID, THE A-PYRONE COMPOUNDS ARE OBTAINED IN A SURPRISINGLY HIGH, ALMOST QUANTITATIVE YIELD. PREFERABLY THE STARTIN $-HALOGENO-B-ALKOXY CROTONIC ACID ESTER IS OBTAINED BY BROMINATING B-ALKOXY CROTONIC ACID ESTER WITH A BROMINATING IMIDO COMPOUND SUCH AS N-BROMO SUCCINIMIDE OR 1,3-DIBROMO-5,5-DIMETHY HYDANTOIN IN THE ABSENCE OF A SOLVENT AT A TEMPERATURE EXCEEDING 100*C., PREFERABLY AT 105-115*C. THE SUCCINIMIDE OR DIMETHYL HYDANTOIN FORMED THERBY ISA COMPLETELY REMOVED FROM THE $-BROMO-B-ALKOXY CROTONIC ACID ESTER BY EXTRACTION OF A SOLVENT WHEREIN THE IMIDO COMPOUNDS ARE SOLUBLE BUT NOT THE BROMO COMPOUND. THE BROMO COMPOUND NEED NOT BE DRIED AND CAN DIRECTLY BE PURIFIED BY VACUUM DISTILLATION. THE YIELD IS ALMOST QUANTITATIVE. WATER IS THE PREFERRED SOLVENT.

Inventors

• 👤 Hans Brinkhoff

Bibliographic Details