Allose. configuration

Allinger, Norman Louis, 130 Allose. configuration of, 982 Allyl aryl ether, Claisen... 

Diacetone allose can be formed from diacetone glucose by first oxidizing die C-3 hydroxyl carbon with acetic anhydride in dimethylsulfoxide [101], followed by reduction with sodium borohydride (reaction 4.95). The reduction forms exclusively the allose configuration. 

Intramolecular cycloadditions of chiral nitrones provide a useful tool for the preparation of bioactive heterocyclic compounds.63 Shing et al. demonstrated that 1,3-dipolar cycloaddition of nitrones derived from 3-0-allyl-hexoses is dependent only on the relative configuration at C-2,3, as shown in Scheme 8.16. Thus 3-0-allyl-D-glucose and -D-altrose (both with threo-configuration at C-2,3) produce oxepanes selectively, whereas 3-O-allyl-D-allose and -D-man-nose (both with erythro-configuration at C-2,3) give tetrahydropyranes selectively.80... 

The above interesting approach to the asymmetric allyltitanation reaction does, however, have a limitation. Thus, L-glucose is much more expensive that the D-form and, consequently, homoallylic alcohols of the opposite configuration cannot easily be obtained by this method. In an attempt to induce the opposite si face selectivity, other acetonide derivatives of monosaccharides from the xylose, idose, and allose series were tested [42b,42c], The enantiofacial discrimination was, however, much lower than that with DAGOH and both re and si face selective additions to aldehydes were observed. 

Figure 9.3 Stereoisomers of the D-aldoses. D-Ribose and D-arabinose differ only in their configuration about a single carbon atom (carbon 2) and are examples of epimers. Diastereoisomers are stereoisomers which are not enantiomers of each other but are chemically distinct forms, the eight D-hexoses being examples. Some, however, are also epimers of each other, for example D-allose and D-altrose. The number of aldoses in the L series is equal to that of the d series and each compound is an enantiomer of one in the other series.

For the first time, DFT theory has been applied to a study of diastereofacial selectivity in 1,3-dipolar cycloadditions of nitrones to di-3,4-dimethylcyclobutene. ° The stereochemical outcome of the INAC reactions of nitrones (49) and (52) derived from 3-(9-allyl-D-hexoses is dependent only on the relative configuration at C(2,3), and thus 3-(9-allyl-D-glucose (48) and -o-altrose (threo configuration) afford oxepanes (50) selectively whereas 3-O-allyl-D-allose (51) and -D-mannose (erythro configuration) give tetrahydrofurans (53) and (54) selectively (Scheme 18). frani-2-Methylene-... 

R. U. Lemieux Application of nuclear magnetic resonance to problems of structure, configuration, and conformation in carbohydrate chemistry J. S. Brimacombe Synthesis of some naturally occurring allose derivatives and some associated chemistry... 

T. Uryu, K. Kitano, and K. Matsuzaki, Ring-opening polymerization of 5,6-anhydro-glucose and 5,6-anhydro-allose derivatives. Effect of substitution or configurational difference at the position of sugar monomers on polymerization behavior, J. Polym. Sci., Part A Polym. Chem., 20 (1982) 2181-2194. 

Moderate asymmetric induction and low yields are observed when the compound 5, prepared from (A, )-hexadienal and (15,25)-pseudoephedrine, undergoes cycloaddition with the nitroso derivative 6. The major cycloadduct 7 is obtained together with minor amounts of diastereomers (d.r. 62 24 11 3) and after chromatography is isolated in 32% yield. Its configuration is first assigned by H NMR, and then by conversion into the known (+ )-(S)-2-methyl-l-(4-toluenesulfonyl)piperidine. Compound 7 is the key intermediate for the total synthesis of an amino allose derivative135. 

Pure allitol (meso configuration m. p. 150-151°) was described for the first time by Lespieau and Wiemann, who synthesized it by the hydroxylation of one of the stereoisomeric forms of divinylglycol. Its structure was established rigorously by Steiger and Reichstein when they demonstrated its identity with the product obtained by the reduction of D-allose. 

It was in 1910 that Levene and Jacobs first applied the classical cyanohydrin synthesis to o-ribose (I), a five carbon atom aldehyde sugar (aldopentose) which had become more readily available through their earlier research on nucleic acids. Two new aldohexoses were thus obtained in sirupy form, and characterized by suitable crystalline derivatives. To one of these sugars was given the name allose, with configuration V, because it should be oxidizable readily to allomucic acid (VIII). The latter is an optically inactive, dibasic acid, described by... 

---