1/10/2024 0 Comments Defaye alpha pdf6) All new compounds were characterized by optical rotation, 300 MHz 1H- and ’ 3CNMR spectroscopy and mass spectrometry. Driguez, Tetrahedron Left., preceding paper. 2) A.Kjaer, in Carbohydrate Sulfates, R.G.Schweiger Ed., Am.77, ACS, Washington, 1977, 19. References and notes 1) Author to whom correspondence should be addressed. Besson for competent graphical performance. Further investigations are currently under way in this laboratory1 to synthesize various classes of artificial glucosinolate analogues and “pseudo-gluwsinolates”. This straightforward synthetic access to the alpha stereoisomers of the natural molecules brings about the opportunity of new comparative enzymic and chemical studies on anomeric pairs of glucosinolates. As a representative example, sequential 0-sulfation (CIS03H, pyridine, CH2Cl2) and de-acetylation (NH3, M H) of the indole compound 6e readily furnished unnatural a-glucobrassicin 26 78. selected nitrile- ides A-CN+-O- generated in situ from the corresponding hy r xamoyl chlorides QT led to the previously unknown Qthiohydroximates $8 9, precursors to the artificial a-GSL 2a and 2d and to the Qanomers 2b, 2c and 2e of natural glucotropaeolin 1b, gluconasturtiin lc and glucobrassicin 18, respectively. Thus, an improved sequence was tailored for the preparation of 2,3,4,6-tetra-oacetyl-I -thio-a-D-glucopyranose S5: treatment of the l&r’ I derivative 3 (obtained as described4 in one step from r%acetochloroglucopyranose % ) with phenylmercuty(ll) acetate quantitatively gave the 1-phenylmercurythio-a-D-glucopyranose 4 which, by reaction with hydrogen sulfide in ethanol, afforded 5 in 56% yield. Besides the reactions recently described4, trityl tetra-0-acetyl-1 -thio-a-Dglycosides can also be converted in high yields into tetra-O-acetyl-l-thio-a-Dglycoses. The trityl group provides a versatile protection of a thiol function in carbohydrate chemistry. their biosynthesis and biodegradation, we have developed a synthetic access to the previously unknown a-anomers 2. In the course of our studies on the elaboration of potent artificial analogues of natural GSL with the aim of understanding i.a. Natural glucosinolates (GSL) 1 occurring mainly in the family ciferae display exclusively a s-D-thioglucosyl configuration at the anomeric carbon%I*. A general synthesis of the of naturally occurring glwosinolatcs is pmposcd b) Laboratoire de Chimie Bioorganique et Analytique, U.R.A.499, Universite d’orleans, B.P.6759, 45667 Orleans Cedex 2, France. ![]() a) Centre de Recherches sur les Macromolecules Vegetales, CNRS B.P.53 X, 36041 Grenoble Cedex, France.
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