Scientia Sinica

No. 1 CHANG: STUDIES ON FUSED RING SYSTEMS II 51

carbon to y-(6-methoxy-2-carboxy-1,2,3,4-tetrahydro-I-naphthyl)-butyric - acid (VII) according to the method of Bachmann and coworkers!”. In the course of the reduction, two diastereoisomers should be produced, but only one principal product was obtained. This crystalline acid was readily resolved with brucine in anhydrous methyl alcohol’ into / and d-acid brucine salts. The former, being the less soluble, readily crystallized out, while the latter, being very soluble in methyl alcohol, was obtained as a yellow gum after the complete removal of the solvent. These two salts were separately hydrolyzed, thus /-y-(6-methoxy-2-carboxy-1,2,3,4-tetrahydro-I-naphthyl)butyric acid and d-y-(6-methoxy-2-carboxy-1,2,3,4-tetrah ydro-1-naphthyl)butyric acid were obtained in pure forms. —

The Lacid and d-acid obtained above were respectively esterified with

diazomethane. The respective dimethyl ester, after Dieckmann reaction and methylation, produced the corresponding mixtures of the diastereoisomeric

keto esters (XI) and (XV):

COOH COOCH;

| (CHa)s Cons JV one 2 SERNG I/F. Jf ca ZN\/N/ LN OCHs OCH3 . I-Acid XK IX A\ C40 \ 1. NaOCH, | | C—OCHs \X 2. CHsl ( ae © LNA NF 3 d—Keto ester XI CH 6 cha O i Lae + Br—CH;—C7 OCH, oH (y oe L/S OCH

d—Hydroxy ester XII