Selective epimerization of L-chiro-inositol to L-muco- and D-chiro-inositol derivatives.
In a one step procedure, L-1-O-benzyl-2-O-methyl-chiro-inositol (1) was acetalized to the L-muco-inositol derivatives 2, 3 and D-2-O-benzyl-3-O-cyclohexylcarbamoyl-4-deoxy-4-(N,N'-dicyclohexylureido)-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (4). Complete conversion of L-1-O-benzyl-6-O-cyclohexylcarbamoyl-3-O-formyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (3) into L-1-O-benzyl-6-O-cyclohexylcarbamoyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (2) is feasible by deformylation in boiling methanolic triethylamine. Furthermore, stepwise deprotection of 2 and 4 is described. Thus, compounds 5, 10, and 7 were obtained by decarbamoylation of 2, 4, and 6, respectively, with boiling methanolic sodium methoxide. The trichloroethylidene group of L-1-O-benzyl-2-O-methyl-4,5-O-trichloroethylidene-muco-inositol (5) was removed in a two step procedure (hydrodechlorination-deacetalization) via the ethylidene acetal 7 to give L-1-O-benzyl-2-O-methyl-muco-inositol (9). On refluxing D-chiro-inositol derivative 4 with 99% acetic acid, the ureido moiety was cleaved generating D-2-O-benzyl-4-cyclohexylamino-3-O-cyclohexylcarbamoyl-4-deoxy-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (11). By contrast, cleavage of the ureido moiety of 10 was relatively difficult. The corresponding D-2-O-benzyl-4-cyclohexylamino-4-deoxy-1-O-methyl-5,6-O-trichloroethylidene-chiro-inositol (12) was only formed in small amounts. The structures of 1, 3 and 10 were confirmed by X-ray analysis.
Miethchen
Ralf
R
Department of Chemistry, University of Rostock, Albert-Einstein-Strasse 3A, D-18051 Rostock, Germany. ralf.miethchen@chemie.uni-rostock.de
Sowa
Christian
C
Frank
Michael
M
Michalik
Manfred
M
Reinke
Helmut
H
D000107:Acetylation; D018360:Crystallography, X-Ray / Q000379:methods; D007294:Inositol / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013237:Stereoisomerism
D007294:Inositol