L-Ristosamine

Products 15 and 16 contain all of the chiral centers and the required functionalities for direct conversion into N-protected L— daunosamine (17) and L-ristosamine (18). This is achieved by N-pro-... 

Many DOHs, such as L-daunosamine, L-epivancosamine or L-ristosamine, contain an amino group at C3, which is introduced by an aminotransferase. The substrate for this reaction is the 3-keto sugar intermediate that arises as a consequence of the action of a 2,3-dehydratase. This transaminahon reaction has been biochemically characterized in the biosynthesis of L-epivancosamine [10]. Using a coupled reaction with EvaB (2,3-dehydratase) and EvaC (aminotransferase), with pyridoxal-5-phosphate (PEP) as a coenzyme and L-glutamate as a cosubstrate, they were able to show conversion of TDP-4-keto-2,6-dideoxyglucose into thymidine-5 -diphospho-3-amino-2,3,6-trideoxy-D-threo-hexopyranos-4-ulose. 

Mendlik, M.T., Tao, P., Hadad, C.M., Coleman, R.S., and Lowary, T.L. (2006) Synthesis of L-daunosamine and L-ristosamine glycosides via photo-induced aziridination. Conversion to thioglycosides for use in glycosylation reactions. Journal of Organic Chemistry, 71 (21), 8059-8070. 

The synthesis of A-benzoyl L-ristosamine (729) parallels that of 615 (Scheme 95) on the basis of anti-111 instead of syn-113 [209]. 

The butyrolactone skeleton of precursors for the sugar component of the glycoside antibiotics L-ristosamine and L-daunosamine can be readily assembled by a nitroaldol reaction of 3-nitropropionate (553) with 831, followed by lactonization [229] (Scheme 111). The initial condensation gives 832 in only moderate yield, probably due to the reversible nature of the nitroaldol reaction. If the crude product is treated with pyridinium tosylate, a mixture of lactones 833 and 834 is produced with concomitant loss of the THP group. The ratio of lactones is dependent on the base used in the nitroaldol condensation. Use of potassium tert-butoxide affords a 2 1 mixture of 833 and 834. The ratio can be increased to 5 1 with KF 2H20/tetrabutylammonium chloride, but the overall yield decreases. 

Reduction of the nitro group and benzoylation affords a mixture of benzamides 558 and 719 that is separable by column chromatography. These benzamides serve as precursors to L-ristosamine and L-daunosamine respectively. 

Oxidation of alcohol 100 to aldehyde 103 with PCC followed by treatment of the unpurified aldehyde with (carbethoxyethylidene)triphenylphosphorane affords a poor yield of a mixture of diastereomeric olefins 104 together with substantial amounts of unreacted 100. This may suggest that PCC oxidation is not the preferred method for optimal oxidation of 100 to 103. Nevertheless, the diastereomeric mixture 104 has been exploited in the synthesis of A -ben-zoyl-2,3,6-trideoxy-3-amino-L-x> /o-hexapyranose (105) [42]. In three steps, 105 is converted to AAbenzoyl-L-ristosamine (106), the aminodeoxy sugar component of the antibiotic risto-mycin [43] (Scheme 24). 

From Chiral Non-carbohydrates - A section on amino-sugars has been included in a review of the synthesis of monosaccharides from non-carbohydrate sources. L-Ristosamine 42 was synthesized by addition of the Cs-synthon 40 (which contains a masked aldehyde function that can be readily demasked by mild acid hydrolysis) to the L-lactaldehyde derivative 41 (Scheme 11). The TBSOP adduct 43 (Vol.27, p.ll4), derived from 2,3-< -isopropylidene-D-glycer-aldehyde, has been converted into 3-amino-3-deoxy-D-altrose 46 by a route involving cis-hydroxylation of its unsaturated lactam moiety and periodate cleavage between C-6 and C-7 of the derived heptitol derivative 45 as key steps (Scheme 12). 3-Amino-3-deoxy-L-allose was obtained by converting 43 to its C-3... 

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... 

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. ... 

The full paper on the synthesis of D-forosamine(4-dimethylamino-2,3,4,6-tetradeoxy-D- ryz/rro-hexose) from (2) has also appeared. Standard transformations have been used in a synthesis of derivatives of L-ristosamine (3-amino-2,3,6-trideoxy-L-ara6i/ >-hexose), and its C-4 epimer, from l-rhamnal. Non-carbohydrate precursors have been utilized for the synthesis of the derivative (3) of racemic daunosamine (3-amino-2,3,6-trideoxy-/j xo-hexose), in a sequence involving allylic amination of a hexenal derivative using a selenium-chloramine T reagent, followed by m-hydroxylation which led to a crystalline product with the required lyxo configuration (Scheme 2). ... 

Addition of hydrazoic acid to the D-ribose derived enal (25) led to a mixture of epimeric azides (26) which were separately converted into N-benzoyl-L-ristosamine (27) and /V-benzoyl-L-acosamine (28) (Scheme 8). 2,3-Dideoxy-3-amino-nucleosides synthesized from a sugar enal derivative, are covered in Chapter 20. The 5-amino-5-deoxy-L-taluronic acid derivative (30) was obtained by addition of succinimide anion to the nitro-olefin (29) followed by ozonolysis, whereas the D-allo-derivative (31) was obtained when the nucleophile was a sulphonamide anion (Scheme 9). ... 

A standard displacement with azide ion, etc., has been used in the conversion of 3,4,7-tri-0-acetyl-2,6-anhydro-5-0-methanesulphonyl-D- /ycero-L-ma/jno-heptonamide (113) into 5-amino-2,6-anhydro-5-deoxy-D- /> ccro-D- w/<7-heptonic acid (114), which, after formation of the methyl ester hydrochloride, underwent polycondensation to give oligomeric or polymeric amides on treatment with methanolic sodium methoxide. Both 3-acetamido-2,3,6-trideoxy-L-hexosides (116) and (117) have been synthesized by introduction of an amino-group via azide-displacement of the allylic acetoxy-group in the glycal derivative (115) (116) and (117) are derivatives of L-acosamine and L-ristosamine, respectively. ... 

Di-O-acetyl-L-rhamnal (115) gave a mixture of (220) (60%), (221) (5%), and (222) (22%) when treated with sodium azide in acetonitrile in the presence of boron trifluoride etherate. The conversion of the epimeric 3-azides (220) into derivatives of L-acosamine and L-ristosamine is noted in Chapter 8. 

Parker KA, Chang W. Regioselectivity of rhodium nitrene insertion. Syntheses of protected ycals of L-damiosamine, D-saccharosamine, and L-ristosamine. Org Lett. 2005 7 1785-1788. 

New compounds reported include the chloropolysporins A-C, produced by a strain of Faenia interjecta, which possess a cyclic polypeptide core with attached D-glucose, D-mannose, and L-ristosamine,... 

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