ChemInform Abstract: A Facile Access to Optically Active Ring C Aromatic Diterpene Derivatives. Highly Efficient Synthesis of (+)‐12‐Methyl‐7‐ oxopodocarpa‐8,11,13‐triene‐13‐carboxylic Acid and (+)‐13‐Methyl‐7‐ oxopodocarpa‐8,11,13‐triene‐12‐carboxylic Acid from Manool.

Abstract

A Facile Access to Optically Active Ring C Aromatic Diterpene Derivatives. Highly Efficient Synthesis of (+)-12-Methyl-7oxopodocarpa-8,11,13-triene-13-carboxylic Acid and (+)-13-Methyl-7-oxopodocarpa-8,11,13-triene-12-carboxylic Acid from Manool. -The high temp. Diels-Alder reaction between the manool derived diene ( I) and methyl 2-butynoate (III) leads to a regioisomeric mixture of aromatized adducts (III) and (IV). After chromatographic separation further benzylic oxidation and alkaline hydrolysis leads to isomeric acids (V) and (VI). Comparison of their spectroscopic properties with natural margolone shows that the previous assignment of structure (V) to margolone is incorrect.-(NAKANO, T.; ALONSO, R.; MAILLO, M. A.; MARTIN, A.; NUNEZ, R. A.; Tetrahedron Lett. 36 (1995) 22, 3801-3804; Cent. Quim., Inst. Venez. Invest. Cient., Caracas 1020-A, Venez.; EN)