Synthesis of Unsaturated Diesters of Primary, Secondary and Tertiary Diols Derived from Dimethyl (+)-Tartrate and Galactaric Acid

JIMENA SCOCCIA, DARÍO C. GERBINO, VICTOR F. TERRAZA, ADRIANA E. ZÚÑIGA, AND JULIO C. PODESTÁ

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2013 p. 4418 - 4426

1434-193X

Some studies connected with the preparation of symmetrical unsaturated diesters of diols derived from dioxolanes protected dimethyl (R,R)-tartrate and galactaric acid (2) are reported. Three methods of esterification were studied in depth. The first one was the reaction of mixed anhydrides, obtained from a,b-unsaturated acids and benzoyl chloride, with diols 3 (primary), 5 (secondary), and 7 (primary), i.e., Yamaguchi-SantaLucía?s method. Using this method only the symmetrical diacrylates of diols 5 and 7 were obtained quantitatively. In the other ten cases studied the reactions led to mixtures of symmetrical and unsymmetrical diesters which were difficult to separate. The mixed anhydrides did not react with the tertiary diols 4 (TADDOL) and 8. The average yield obtained in desired symmetrical diesters in the 12 cases studied was 54%. The acylation of the diols with the anhydrides of the unsaturated acids, showed to be an excellent method that led in the 12 cases studied to the symmetrical unsaturated diesters of diols 3, 5, 7 as only products of reaction, in an average yield of 83%. Unfortunately, the method could not be applied to the diesters derived from the tertiary diols 4 (TADDOL) and 8. The third method studied was the reaction between the alkoxides prepared with solutions of nBuLi in ether with the unsaturated acids chlorides at -50 °C, i.e., Kaiser-Woodruff protocol. This showed to be the best of the three methods tested. The method was applied with success to the synthesis of the desired unsaturated diesters derived from diols 3, 4, 5, 7, and 8. The average yield of the 19 cases studied was of 78%.