著者

大船 泰史

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.24, pp.560-567, 1981-09-10

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I. (-)-Domoic acid (2) isolated from Rhodophyceae (Chondria armata Okamura), possessing strong neuroexciting activity, has been synthesized in optically pure form. The reported structure was (2S,3R,4S) 1 with undefined stereochemistry at C-5' carbon atom. Including determination of C-5' configuration, we planned to synthesize 1 as a target molecule. Comparison of both synthetic epimers 21a and 21b with natural domoic acid derivative showed uncorrectness of the structure 1. So, X-ray crystallographic analysis was examined by Takemoto et al. As a result, structure 1 was revised to 2 with C-2', C-3' Z double bond and C-5' R configuration. The synthesis to 1 and then, 2 are in the following. 1) C-3 and C-4 side chain of the pyrollidine ring were introduced by means of Diels-Alder reaction (6 and 4-methyl-2-trimethylsilyloxy-trans-1,3-butadiene). 2) Chemoselective reduction of C-5 amide function in the presence of N-t-Boc protecting group was achieved using BH_3-DMS (9→10) 3) C-4 side chain (13→20a,20b) was constructed in four steps via hydroxyselenenylation and selenoxide elimination, followed by Wittig reaction with 18a (C-5'R) and 18b (C-5'S). Wittig reaction of 18a and 16b afforded 22, which was converted in three steps to (-)-domoic acid (2). II. 2'-Deoxymugineic acid (25) isolated from wheat root (Triticum aestivum L.) and avenic acid A (26) isolated from oat root (Avena sativa L.) were synthesized in the stereospecific manner employing N-alkylation procedure of three optically active unit.