67(PA2-7) ガランチナミン酸の合成研究 : 鎖状アリルアミン系における1,2-立体制御(ポスター発表の部)

概要

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Approaches to the synthesis and structural elucidation of galantinamic acid (2), a constituent amino acid of a peptide antibiotic galantin I (1) isolated from Bacillus pulvifaciens, are described. Since absolute as well as relative stereochemistry have not, yet, assigned to 2, syntheses of the eight diastereoisomers with the 3 different chiral centers derivable from L- or D-lysine are required. The synthetic Scheme involves initial construction of the threo and erythro vicinal amino hydroxyl systems at C5 and C6, respectively. These were achieved, highly stereoselectively, by the following two methods: (i) MCPBA epoxidation of the hydroxy allylamine 11 provided the threo epoxide 12 as the sole product, and (ii) S_N2 cyclic carbamate formation of the silyl carbamate prepared from 19 gave the erythro product 20, exclusively. Four isomeric unsaturated esters 17, 18, 23, and 24, prepared stereoselectively from the two diols, 13 and 21, were converted into eight diastereomeric triacetate 25ab, 26ab, 27ab, and 28ab. One of the isomers 28a or 28b was found to be identical with naturally derived triacetate. Thus relative stereochemistry of 2 at C5 and C6 was confirmed to be either 2a or 2b. Efforts to determine the stereochemistry of the C3 in relation to the C5 center and the absolute structure of 2 are in progress.
天然有機化合物討論会の論文
1987-07-25