3-C-methyl-D-allose

The utilization of the furanoid 3-C-methyl-D-allose building blocks 57 and 60 for a convergent total synthesis of ACRL Toxin I in the form of its stable 3-0-methyl ether (63) involved their conversion into enantiomerically uniform connective segments. The key feature of the retrosynthesis was the expectation... 

Photolysis of 3-0-acetyl-3-C-methyl-l,2 5,6-0-isopropylidene-o -D-allo-furanose yielded the corresponding 3-deoxy-3-C-methyl-D-allose derivative (see... 

The pyranoisoxazolidines 20 and 21 are readily obtained by intramolecular cycloadditions of the nitrones formed by reaction of 7V-benzylhydroxylamine with 3-0-allyl-3-C-methyl-D-allose and 3-0-allyl-l,2-0-isopropylidene-3-C-methyl-a-D-ri o-pentodialdofuranoside, respectively. The latter two compounds are available from a common precursor, 3-D-allyl-l,2 5,6-di-0-isopropylidene-3-C-methyl-a-D-fl//o-pentofuranose. Compound 20 was further converted to the pyranoid 22, whilst 21 was converted to the enantiomer of 22 by standard chemistry. Oxepane cycloadducts are also produced when 3-0-allyl-3-C-methyl-a-D-xylo- or 3-0-allyl-a-D-r/ho-pentodialdofuranose is used. (See also Vol. 27, p. 203, ref. 25 for related work). ... 

Reaction of Methyl 4,6-0-Benzylidene-3-C-methyl-2-0-p-tolylsulfonyI-a-D-allo-pyranoside with Sodium Methoxide in Methyl Sulfoxide Synthesis of 6-Deoxy-3-C-methyl-3-O-methyl-D-allose (2-Hydroxy-D-cladinose), G. B. Howarth, W. A. Szarek, and J. K. N. Jones, Carbohydr. Res., 11 (1969) 257-262. 

V0I.17, p.l20). These oligosaccharides incorporate D- and L-cymarose, D-oleandrose, 6-deoxy-3-0-methyl-D-allose, and the unusual ether-linked glucosyl olivose wilforibiose (2) as con-stltuent sugars, and their H- and - C-n.m.r. characteristics have been tabulated.- ... 

Deoxy-2-0-methylallose, D-34 6-Deoxy-3-0-methyl-D-allose, D-34 3-Deoxy-3-C-methylallose, D-289 6-Deoxy-4-0-methyl-D-altrose, D-37... 

P2j Z = 2 D = 1.17 R = 0.080 for 3,888 intensities. This is aconfigu-rational analysis of the macrolide antibiotic 23672RP from Streptomyces chryeus. All three sugar residues are pyranoid the conformation of the a-ketose is CX, with Q = 56 pm, 0 = 9° that of the / -D-mycinose (6-deoxy-2,3-di-0-methyl-D-allose) is 4Clt with Q = 59 pm, 0 = 6° and that of the / -L-mycarose (2,6-dideoxy-3-C-methyl-L-riho-hexose) is 1C4, with Q = 53 pm, 0= 177°. The O-5-C-l-O-l-C glycosidic torsion-angles are —71, —87, —83°. The atomic coordinates reported in the paper refer to the opposite enantiomer. 

This interesting transformation from a readily available 6-deoxyhexose forms the basis for the synthesis231 of 6-deoxy-2,3-di-0-methyl-D-allose (mycinose),168 one of the carbohydrate moieties of the antibiotic chalco-mycin. The synthesis merely involves the protection of the C-5 hydroxyl group in (41) by benzylation, followed by partial hydrolysis with acid, methylation of the product at the C-2 and C-3 hydroxyl groups, and debenzylation. 

Another highly versatile building block derived from diacetone-glucose 54 is the 1,2-acetonide of 3-C-methyl-a-D-allose in its furanoid form 57, which has been utilized as the key compound in a convergent total synthesis of ACRL Toxin I (63). Its elaboration from 54 starts with a pyridinium dichromate / acetic anhydride oxidation (64), is followed by carbonyl olefination of the respective 3-ulose with methyl (triphenyl)phosphonium bromide and hydrogenation (— 55 56), and is completed by acid cleavage of the 5,6-isopropylidene group. This four-step process 54 -> 57, upon optimization of reaction conditions and workup procedure, allows an overall yield of 58 % (63), as compared to the 22 % obtained previously (65). 

C N.m.r. measurements have been used to assign the configuration of the branch carbon in pairs of 3-C-hydroxymethyl and 3-C-methyl branched-chain l,2 4,6-di-0-acetalated hexopyranose derivatives by comparison with the Z and E isomers of 4-t-butyl-l-hydroxymethylcyclohexanol and with corresponding diacetals of o-glucose and D-allose, ... 

Two of the four possible diastereoisomeric 2,3 5,6-di-0-ethylidene-j3-D-allofuranoses have been isolated following acid-catalysed condensation of D-allose with acetaldehyde. Examination of the diastereoisomers and derivatives thereof by H n.m.r. spectroscopy established the configuration of the C-2 atom in the 2,3-O-ethylidene ring as R and as either R or S in the other acetal ring. Condensation of 3-0-benzyl-D-allose with acetaldehyde gave, after acetylation, 1,2-di-0-acetyl-3-0-benzyl-4,6-0-ethylidene-)8-D-allopyranose, 5,6-di-O-acetyl-3-0-benzyl-l,2-0-(jR)-ethylidene-a-D-allofuranose, and two diastereoisomeric 3-0-benzyl-l,2(R) 5,6-di-0-ethylidene-a-D-allofuranoses. An alternative route to related diastereoisomeric 1,2-O-ethylidene-a-D-allopyranoses, via reduction of acetoxonium-ion intermediates, is shown in Scheme 21, while acid-catalysed condensation of methyl 4,6-0-benzylidene-a-D-allopyranoside... 

L-mycarose, 2,6-dideoxy-3-C-methyl-L-ribohexose L-cladinose, 2,6-dideoxy-3-0-methyl-3-C-methyl-L-ribohexose L-arcanose, 2,6-dideoxy-3-O-methyl-3-C-methyl-L-xylohexose L-oleandrose, 2,6-dideoxy-3-0-methyl-L-arabohexose D-lankavose, 4,6-dideoxy 3 -0-methyl-D-xylohexose D-mycinose, 6-deoxy-2,3-di-0-methyl-D-allose D-mycaminose, 3,6-dideoxy-3-dimethylamino-D-glucose D-desosamine, 3,4,6"trideoxy-3-dimethylamino-D-xylohexose forosamine, 2,3,4,6-tetradeoxy-4-dimethylaminohexose... 

Chemical Synthesis.—Purine nucleoside 5 -monophosphates enriched with or 0 on the phosphate group are conveniently prepared by treating phosphorus pentachloride in dry triethyl phosphate with one equivalent of the appropriately labelled water to give PO]- or P 0]P0Cl3, which is not isolated but mixed with adenosine or guanosine in the same solvent. Work-up of the resulting 5 -phos-phorodichloridate in similarly labelled water permits the formation of pO]-or P 0]AMP (or GMP) in fair yield with good enrichment. The 5 -monophos-phates of the 5 -C-methyl uridines derived from 6-deoxy-D-allose and 6-deoxy-L-talose have been prepared via phosphorylation of the 2, 3 -0,0-ethoxymethyl-idene derivative of the nucleosides (1) with -cyanoethyl phosphate and DCC or TPS-Cl. The same method has been used to phosphorylate iV -benzoylated 2, 3 -0,C -isopropylidene derivatives of various 5 -C-alkyladenosine species (2) and also 4 -allyladenosine (3) as part of a study in which derivatives of AMP... 

Metiiyl-p-D-allopyranose, A-86 Methylallosamidin, A-85 3-C-Methylallose, M-224 2-O-Methyl-DL-allose, A-86... 

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