ISSN:
0947-3440
Keywords:
Acivicin
;
Photochemistry
;
1,3-Dipolar cycloadditions
;
Nitrile oxides
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
α-Amino-3-chloro-4,5-dihydro-5-methyl-5-isoxazoleacetic acid (8), a ring-methylated analogue of the potent antitumor agent acivicin (AT-125), is synthesized in a 6-step procedure in 63% overall yield from (S)-valine. Key step is the 1,3-dipolar addition of bromonitrile oxide to the N,C-protected (S)-isodehydrovaline (6) available from (S)-valine in four steps involving the photoisomerization of N-phthaloylvaline methyl ester (1). The stereochemical course of the 1,3-dipolar cycloaddition is proven by means of a X-ray structure analysis of the major diastereoisomer 7a formed in the chloronitrile oxide cycloaddition. The absolute configuration of the major (u) diastereomer 7a and the bromo derivative 7b is (αS,5R).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199519950486