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[摘要]：The mol. structures of 2-(3'-bromo-4',5'-dihydroisoxazol-5'-yl)-1-tert- butoxycarbonylaminocyclopropanecarboxylic acid (?-10a and 1-amino-2-(3'-hydroxy-4',5'-dihydroisoxazol-5'-yl)cyclopropanecarboxyli c acid (?-11b were detd. by single crystal x-ray diffraction method. The geometrical features and the intermol. interactions of the two diastereoisomers have been compared evidencing a different conformation of the dihydroisoxazole ring: in (?-10a is almost planar, while in (?-11 adopts an envelope shape. Intermol. hydrogen bonds of OH...O and NH...O type in (?-10a det. the formation of a three-dimensional network, whereas in (?-11b polymeric chains due to NH...O interactions are obtained. These compds. are key intermediates of conformationally constrained glutamic acid homologs and the opposite stereochem. of C(3) leads to different pharmacophoric distances, important for the ligand-receptor interaction. The results of the x-ray mol. structures have been complemented by theor. calcns. |
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