Iodonium ion-assisted synthesis of a tetrameric fragment corresponding to the cell wall phenolic glycolipids of Mycobacterium kansasii serovar I

Article abstract of DOI:10.1016/0040-4020(96)00035-X

Two procedures are described towards the assembly of the tyramine spacer-containing tetramer 5, a derivative of the phenolic glycolipid of Mycobacterium kansasii serovar I. First, iodonium ion-mediated glycosylation of trimeric acceptor 2a with D-rhamnopyranoside donor 10 gave fully protected tetramer 17. Selective removal of the chloroacetyl group of 17, subsequent deoxygenation and removal of the protective groups, led to target 5. The potential occurrence of double stereodifferentiation (DSD) was examined by condensation of L-fucopyranoside model acceptor 14 with both the enantiomeric rhamnopyranoside donors 10 and 13. The second procedure involves elongation of trimeric acceptor 2b with 6-deoxy-D-glucopyranoside 28. Desulfurisation of the resulting tetrameric fragment 36 followed by hydrogenation of 37 gave 38, the phenylacetyl (PhAc) of which was enzymatically removed to yield target tetramer 5.