SOME DERIVATIVES OF 3-DEOXY-D-GLYCERO-D-GALACTO-NON-2-ULOSONIC ACID (KDN)

Treatment of a solution of 3-deoxy-D-glycero-D-galacto-non-2-ulosonic (KDN) in 11 N aqueous hydrochloric acid with an excess of ethanethiol gave in 52% yield the diethyl dithioacetal of the corresponding 1,4-lactone, which was further characterized as its peracetate. With 1,3-propanedithiol, only one thiol function reacted and the product, isolated in 18% yield as its peracetate, was a vinyl thioether of the alpha,beta-unsaturated 1,4-lactone. The methyl ester methyl beta-glycopyranoside derivative of KDN could be converted to the 8,9-isopropylidene ketal 7 (69%). Conditions were found which allow selective silylation at C-4 with tert-butylchlorodimethylsilane, giving the 4-O-tert-butylsilyl derivative in 91% yield. Heating it with bis(tributyltin) oxide afforded the 1,7-lactone with inversion of the ring conformation. Lithium aluminium hydride reduction of 7 afforded the corresponding methyl non-2-ulopyranoside, which was converted to the 1,4-bis(silyl) ether. Bromination of 1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol in aqueous solution at 0 degrees C with N-bromophthalimide gave a mixture of bromodeoxy hexoses from which 2-bromo-2-deoxy-D-mannose was isolated in 60% yield by crystallization. Its incubation with pyruvate in the presence of sialyl aldolase gave 5-bromo-3,5-dideoxy-D-glycero-D-galacto-non-2-ulosonic acid 16 in 70% yield.