Synthesis of 4,6:2',3':4',6'-tri-O-cyclohexylidene-alpha,alpha'-trehalose 2-palmitate: an intermediate for the synthesis of mycobacterial 2,3-di-O-acyl-alpha,alpha'-trehalose antigens. 1994

P A Wallace, and D E Minnikin
Department of Chemistry, University of Newcastle, United Kingdom.

The aim was to 'triprotect' trehalose by placing various acetals, or related protecting groups, across the 4,6-, 2',3'-, and 4',6'-positions, leaving the 2,3-positions free for subsequent acylation. Isopropylidene and ethylidene acetals were studied, with the formation of a small amount of 4,6:2',3':4',6'-tri-O-isopropylidene-alpha,alpha'-trehalose. 4,6:4',6'-Di-O-benzylidene-2',3'-O-(tetraphenyldisiloxane-1,3-d iyl)-alpha, alpha'-trehalose 2,3-diacetate was prepared in low yield. 1,1-Dimethoxycyclohexane reacted with methyl alpha-D-glucopyranoside to afford the 4,6-O-cyclohexylidene derivative, isolated as the diacetate; mild acid cleavage of the acetal gave the 2,3-diacetate. 4,6:2',3':4',6'-Tri-O-cyclohexylidene-alpha,alpha'-trehalose is the major product of the reaction between alpha,alpha'-trehalose and 1,1-dimethoxycyclohexane. 2,3:4,6:2',3':4',6'-Tetra-O-cyclohexylidene-, 4,6:4',6'-di-O-cyclohexylidene-, and 4,6-O-cyclohexylidene-alpha,alpha'-trehaloses were also isolated in lower yields, all acetals being characterised as their peracetates. The proportions of the different trehalose acetals were dependent upon the molar ratio of 1,1-dimethoxycyclohexane and particularly on the reaction temperature. The triprotected trehalose acetal was acylated with palmitic acid, with excellent regioselectivity, affording the 2-O-palmitoyl ester. This 2-monoacylated, triprotected trehalose is a key intermediate for the synthesis of 2,3-di-O-acyl-alpha,alpha'-trehalose glycolipid antigens, isolated from Mycobacterium fortuitum and Mycobacterium tuberculosis.

UI MeSH Term Description Entries
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009161 Mycobacterium A genus of gram-positive, aerobic bacteria. Most species are free-living in soil and water, but the major habitat for some is the diseased tissue of warm-blooded hosts. Mycobacteria
D002240 Carbohydrate Sequence The sequence of carbohydrates within POLYSACCHARIDES; GLYCOPROTEINS; and GLYCOLIPIDS. Carbohydrate Sequences,Sequence, Carbohydrate,Sequences, Carbohydrate
D000215 Acylation The addition of an organic acid radical into a molecule.
D000942 Antigens, Bacterial Substances elaborated by bacteria that have antigenic activity. Bacterial Antigen,Bacterial Antigens,Antigen, Bacterial
D014199 Trehalose

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