Study on the Regioselectivie of Grignard Reagent Addition Reaction of Maleopimaric Acid Trimethyl Ester

Two regioselectivite adducts (compounds 3 and 4) were firstly synthesized from the Grignard reagent and maleopimaric acid trimethyl ester (2). The structures of all compounds were characterized by elemental analyses, NMR and MS, and stero-structures of 3 were further determined by COSY, HMQC and HMBC. The spatial structure of 3 was further confirmed by X-ray single crystal diffraction analysis method. Owing to the addition reaction selectivity of 2 was dependent on the steric hindrance of three methyl groups, the TADDOL (tetraaryl-1,3-dioxolane-4,5-dimethanols) product was prevented because of the formation of lactone 3, but the stereo-structure of the rosin-ring did not changed. Products of 3 and 4 are expected to apply as chiral derivatization reagents. Keywords maleopimaric acid trimethyl ester; grignard reagent; 2D NMR; regioselectivity