The structure of the amino sugars from the antibiotic actinoidin

Syntheses of 2,3,6-trideoxy-3-amino- and 2,3,6-trideoxy-3-nitrohexoses

“…The overall yield was 31 %. Using a procedure nearly identical with that of Pauls and Fraser-Reid, Cardillo and co-workers54 also prepared 49. Brimacombe and co-workers55 reported the preparation of daunosamine (1) from L-rhamnose (42) shown in Scheme V; as in numerous other sequences, an acosamine derivative served as an intermediate. Sequential protection of the 2,3-hydroxyl functionality in the methyl glycoside 54 of L-rhamnose (42) as the benzylidene derivative (a,a-dimethoxytoluene, TsOH, DMF; oxymethyl (MOM) derivative provided 55.…”

“…(Although this preparation represents a formal total synthesis of L-acosamine (4), the sugar was not isolated from natural sources until 1973. 42,43) The configuration of the C-4 hydroxyl in 46a was inverted through reaction of the mesylated 3-azido sugar 46b with sodium benzoate;44 subsequent hydrolysis produced the azido alcohol 48 with the L-lyxo configuration. Catalytic hydrogenation of 48 under acidic conditions gave the crystalline hydrochloride salt of methyl daunosaminide (49).…”

“…An elegant, efficient synthesis of In this sequence, shown in Scheme IV, rhamnose (42) was initially converted to rhamnal (43),40,48 which was solvolyzed in acidic methanol to the hex-2-enopyranoside 5049"51 (53% yield from 42). Epimerization of the 4-hydroxyl group in 50 through Mitsunobu re-action52 (DEAD, PPh3, PhC02H) followed by basic hydrolysis of the benzoate group provided 51a.…”

“…Brimacombe and co-workers56,172 performed the total synthesis of L-ristosamine (8) shown in Scheme XXXI from the keto sugar 56 that they originally prepared from L-rhamnose (42) in conjunction with their preparation of daunosamine (l).55 Reaction of 56 with aqueous hydroxylamine hydrochloride furnished the oxime derivative 179, which on catalytic reduction over Adams' catalyst in the presence of acetic anhydride gave methyl N-acetylristosaminide (180) in 62% yield (13% from 42).…”

“…Brimacombe and co-workers213,214 reported a synthesis of L-4-epi-vancosamine (16) (Scheme XLIX) in which the dialdehyde 261, obtained by oxidation of rhamnose (42) with sodium metaperiodate,145,146 was condensed with basic nitroethane219 to produce the nitrohexose 262 in 12% yield. In the preferred route, the methyl glycoside moiety in 262 was hydrolyzed with dilute hydrochloric acid, and the free nitro sugar was peracetylated to the triacetate derivative.…”