4- Amino-2,4,6-trideoxy-L-hexose

Amino-2,3,6-trideoxy-L-hexoses fA-D in Scheme 3 9 occur naturally, forming the gly-cone part of anthracychnone andbiodcs, important in and-tiimor treatment ... 

A simple, divergent, asymmetric synthesis of the four stereoisomers of the 3-amino-2,3,6-trideoxy-L-hexose family was proposed by Dai and coworkers [222], which is based on the Katsuki-Sharpless asymmetric epoxidation of allylic alcohols (Scheme 13.115). Recently, A-trifluoroacetyl-L-daunosamine, A-trifluoroacetyl-L-acosamine, A-benzoyl-D-acosamine and A-benzoyl-D-nistosamine were derived from methyl sorbate via the methyl 4,5-epoxy-( -hex-2-enoates obtained via a chemoenzymatic method [223]. 

Chiral auxiliaries have been employed in syntheses of amino-sugars. Precursors (74)-(77) of all the isomers of 3-amino-2,3,6-trideoxy-L-hexose have been synthesised as shown in Scheme 22... 

D. Horton and W. Weckerle, A preparative synthesis of 3-amino-2,3,6-trideoxy-L-7yxo-hexose hydrochloride from D-mannose, Carbohydr. Res. 44 221 (1975). 

L-Daunosamine (166) (R=H), (3-amino-2,3,6-trideoxy-L-/yxo-hexose), is an essential component of both natural and unnatural anthracycline antitumor agents. The 1,3-addition of ketene silyl acetal 164 to the chiral nitrone (Z)-[(4i )- ra 5-2,2,5-trimethyl-l,3-dioxolan-4-yl]methylene[(l S)-l-phenylethyl] amine 7V-oxide (163), prepared by the conversion of 141 to 103 [62] and then reaction of 103 with the hydroxylamine 162, provides the 0-silylated addition product 165 in quantitative yield with an anti relative stereochemistry at C-3 and C-4 (anti syn =>100 1). Efficient transformation of 165 to 166 (R=COPh) is achieved in three steps [63] (Scheme 39). 

The syntheses of glycosides and esters of daunosamine (3-amino-2,3,6-trideoxy-L-/yxo-hexose) suitable for use in the synthesis of analogues of dauno-mycin and daunosamine-containing oligosaccharides have been reported. Methyl (methyl 3-acetamido-2,3-dideoxy-a-D- fe< -hexopyranosid)uronate (6) has been described in which the carboxylate grouping was established from the corresponding 6-azide by sequential photolysis, mild hydrolysis, and oxidation of the 6-aldehydo group. 

Actaplanin, a new glycopeptide antibiotic from Actinoplanes missouriensis, is a complex of at least six components, all containing the same peptide core, the amino-sugar L-ristosamine (3-amino-2,3,6-trideoxy-L-ribo-hexose), and varying amounts of glucose, mannose, and rhamnose. Muraceins A, B, and C, three... 

Amino-2,3,6-trideoxy-arfl6wo-hexose D-/orm, A-458 3-Amino-2,3,6-trideoxy-ara i7W-hexose ij-form, A-458 3-Amino-2,3,6-trideoxy-4-0-methyl-L-araZ in -hexose, 9CI, A-458... 

A synthesis of -acetyl-L-acosamine(3-amino-2,3,6-trideoxy-L-ara >/ o-hexose) (1) has been described, starting from a derivative of sorbic acid (2) (Scheme 1). ... 

Similarly, 1,4-addition of azide to L-e yt/iro-hex-2-enopyranose provided a stereoselective route to the methyl and benzyl glycosides of L-acosamine (3-amino-2,3,6-trideoxy-L-am6ino-hexose). Inversion at C-4 yielded the L-daunosamine analogues, in the same manner as detailed above (ref. 23). Sugar aldehydes have been chain extended to unsaturated N-methylthiazolium salts such as (39) and (41), which were converted through Michael addition of benzylamine, to the 3-amino-2,3-dideoxy-0(-D-t/irco-pentopyranoside (40) and the 7-deoxy-6-e/7i-lincosamine derivative (42) as shown in Schemes 8 and 9, respectively. 3-epi-... 

Daunosamine (3-amino-2,3,6-trideoxy-L-/yjco-hexose) hydrochloride (127) has been prepared in 40% yield overall from methyl a-o-mannopyranoside by the route shown in Scheme 48. A key step in this sequence is the conversion of methyl 2,3 4,6-di-0-benzylidene-a-D-mannopyranoside into the 2-deoxyhexo-pyranosid-3-ulose (126) using butyl-lithium in hexane. 

Following their recent synthesis of daunosamine (3-amino-2,3,6-trideoxy-L-/yxo-hexose) from methyl a-D-mannopyranoside (see Vol. 9, p. 62), Horton and Weckerle have described a related and high-yielding route to 3-amino-2,3,6-trideoxy-D-r/6o-hexose (110), the 5-epimer of daunosamine and the enantiomer of the naturally occurring amino-sugar ristosamine. " A closely related synthesis has afforded the ristosamine derivative (111), which is a key... 

Amino-sugar Derivatives.—3-Amino-2,3,6-trideoxy-L-/yxo-hexose (daunosamine, in a structural investigation of carminomycin), 4-amino-4-deoxy-D-glucose, 2-deoxystreptamine, and a 2,7-diamino-2,3,7-trideoxyoctadialdose (all components of apramycin), 5-0-benzoyl-a-D-arabinofuranosyIcarboxamide, ... 

Attempted direct extension of the two foregoing methodologies to synthesis of the 3-C-methyl analogs of 17, 18, 23 and 24 starting from the diastereoisomeric methyl ketones 10 and 12 was ineffective, as ammonia does not add across the triply substituted double bond of the 3-C-methyl analogs of the esters 19 and 20. However, the phenyl-sulfenimines 25 and 26 add allylmagnesium bromide and diallylzinc with different stereochemistry (8), so that it is possible to have eventual access to the four configurational isomers of 3-amino-2,3,6-trideoxy--3-C-methyl-3-L-hexose. 

Dideoxy-3-C-methyl-4-(methylamino)-D-altrose (22) 3-Amino-2,3,6-trideoxy-3-C-methyl-L-/j/xo-hexose (23)... 

There has been substantial activity in the synthesis of 3-amino-2,3,6-trideoxy-hexoses and their di-A-methyl derivatives as a result of their wide occurrence in antibiotics. In a paper of substantial proportions, Bartner et alP have synthesized by standard reactions all four possible methyl 2,3,6-dideoxy-3-dimethylamino-a-D-hexopyranosides (and some /3-anomers) as well as the corresponding L-ribo isomer (L-megosaminide). Syntheses have been reported for D-ristosamine (3-amino-2,3,6-trideoxy-D-rz7 o-hexose) from methyl 2-deoxy-D-amfcmo-hexo-pyranoside and of the isomeric 3-amino-2,3,6-trideoxy-L-Jcy/o-hexose (1) from methyl 2,6-dideoxy-L- mZ>mo-hexopyranoside, using standard sequences involving azidej displacement of sulphonate esters for introducing the nitrogen. 

There has been a continuing interest in syntheses of 3-amino-2,3,6-trideoxy-hexoses such as daunosamine (9), acosamine (10), etc. In an interesting paper by Fronza et the two sugars have been synthesized from the non-carbohydrate compound (11), which was obtained in 25-30% yield from the incubation of cinnamaldehyde v th acetaldehyde in the presence of bakers yeast (Scheme 2). The crucial amino-lactone (12) was also synthesized from L-threonine. The same authors have also completed their synthesis of A-benzoyl-L-ristosamine (3-benzamido-2,3,6-trideoxy-L /6o-hexose) from 3-benzamido-2,3,6-trideoxy-L-xy/o-hexono-1,5-lactone (Vol. 13, p. 79). An alternative synthesis of methyl A-acetyl-a-L-acosaminide (13) has been described by reduction of the appropriate acetylated oxime by diborane. The thioglycoside (14) was also prepared. ... 

Me 3-Amino-2,3,6-trideoxy-4-0-methyl-L-axebino-hexose, 9CI. Actinosamne [41094-25-1]... 

Amino-2,3,6-trideoxy-/j xo-hexose D-form, A-461 3-Amino-2,3,6-trideoxy-/ xo-hexose L-form, A-461 3-Amino-2,3,6-trideoxy-W >o-hexose L-form, A-462... 

Methyl 4-C-acetyl-2,6-dideoxy-a-L-A7/o-hexopyranoside, A-18 Methyl 4-C-acetyl-2,6-dideoxy-p-L-xj /o-hexopyranoside, A-18 Methyl 3-0-acetyl-2,6-dideoxy-a-D-/j xo-hexopyranoside, D-610 Methyl 4-0-acetyl-2,6-dideoxy-3-0-methyl-DL-ara >ino-hexose, D-607 Methyl 3-amino-2,3,6-trideoxy-a-L-/ xo-hexopyranoside, A-461 Methyl 3-amino-2,3,6-trideoxy-3-C-methyl-a-L-W >o -hexopyranoside, A 65... 

Amino-2,3,6-trideoxy-3-C-methyl-xy/o-hexose L-Pyranose-ybrm, A-466 3-Amino-2,3,6-trideoxy-3-C-methyl-riho-hexose D-form, A-465 2-Amino-2,3,5-trideoxy-3-methyl-D-lyxonic acid, A-427 2-Amino-2,3,5-trideoxy-3-metl]yl-L-ribomc acid, A-427... 

L-/> jco-hexose 4-epimer/ and also for methyl 3-amino-2,3,6-trideoxy-)3-L-jcy/o-hexopyranoside by two closely related sequences involving the unsaturated azido sugar (13). ... 

An improved synthesis of D-kijanose utilizes the trifluoroacet-amido branched-chain sugar (48) to produce the aziridino-inter-mediate (49), which on azidolysis gives mainly the required D-xylo derivative (50), a known precursor for kijanose (Scheme 11) Brimacombe s group have also reported the synthesis of the antibiotic sugar 3-amino-2,3,6-trideoxy-3-C-methyl-L-xylo-hexose usina... 

Benzamido-2,3,6-trideoxy-D-/yxo-hexose, A-461 3-Benzamido-2,3,6-trideoxy-L-/j xo -hexose, A-461 3-Benzamido-2,3,6-trideoxy-L-W/)o -hexose, A-462 Benzyl 3-amino-3-deoxy-p-D-altropyranoside, A-165 Benzyl 2,3-diacetamido-4-0-benzyl-2,3-dideoxy-a-D-xylopyranoside, D-462... 

Amino-1,6-anhydro-4-deoxy-j8-D-mannopyranose (11) and the corresponding D-altrose derivative (12) have been prepared by the sequence outlined in Scheme 9. Multi-stage syntheses using conventional procedures have been reported for derivatives of L-holantosamine (4-amino-2,4,6-trideoxy-3-0-methyl-L-araWw-hexose) and of L-epiholantosamine, the corresponding... 

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