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Paper | Regular issue | Vol 36, No. 6, 1993, pp.1279-1285
Published online, 1st January, 1970
DOI: 10.3987/COM-92-6281
Progress towards a Practical Total Synthesis of Calabar Alkaloids: Total Synthesis of (-)-Esermethole and (-)-Physovenol Methyl Ether from (3S)-1,3-Dimethyl-3-carboxymethyl-5-methoxyoxindole

Qian-sheng Yu, Wei-ming Luo, Yi-qun Li, and Arnold Brossi*

*National Institute of Diabetes and Digestive and Kidney, National Institute of Health, Bethesda, MD 20892, U.S.A.

Abstract

Chemical resolution of the oxindoleacetic acid (7) with brucine in water yielded the acid (7a) of (3S)-absolute configuration. Acid (7a), in using conventional methods, was converted into nitrile (8a), lactone (9a) and amides (10a), and (11a) respectively. Amide (10a), on reduction with LAH in refluxing THF, directly yielded (-)-esermethole (12a), and amide (11a) similarly gave (-)-N1-benzylnoresermethole (13a). Reduction of ester (6a) with LAH in refluxing THF yielded (-)-physovenol methyl ether (14a).