Altrose, »-, derivatives

Synthese der 2-Thio-D-glucose und einiger 3-Thio-D-altrose-Derivate, by E. Hardegger and W. Schiiep, Helv. Chim. Acta, 53 (1970) 951-959. 

The low reactivity of l,6-anhydro-2,3,4-tri-0-benzyl-/3-D-allopyra-nose is also of interest.106 This monomer has 1,3-interaction between substituents on C-2 and C-4 in the C4(d) conformation. However, when conversion into a boat conformation, as proposed, occurs on reaction with a propagating cation, eclipsed bonds develop at C-2, C-3, and C-4. It is, therefore, not surprising that the D-allo anhydride is less reactive than those of D-mannose, D-glucose, or D-galactose. The corresponding, D-altrose derivative has only one axial substituent in addition to the anhydro ring, and these are on opposite sides of the pyranose ring, and therefore do not interact it would be expected to be, and has proved to be, of very low polymerizability.106... 

An important conversion of exo-glycals for our work on altromycin was hydroboration (Scheme 4). We observed that the exo glucal 27 of entry 10 led to a 3/1 ratio of a(28) and J C-glycosides. By contrast, similar treatment of the altrose-derived glycal 29 of entry 11 afforded a 1/10 ratio. Since our program required an a-C-glycoside, the product 28 was carried further to finally produce an altromycin model compound.(2/)... 

Since acid hydrolysis of methyl a-D-altroside leads principally to D-altrosan, it became necessary to resort to other devices in order to complete the transformation to the free sugar. The pioneer work of Robertson and his collaborators had established a clear route from D-glucose to many D-altrose derivatives. The final steps, as described by Richtmyer and Hudson, are the acetolysis of methyl o-o-altroside (XXXVIII), or more simply of its benzylidene derivative (XXXVII), followed by catalytic deacetylation of the pentaacetyl-a-D-altrose thus produced. In this way crystalline D-altrose becomes readily available. 

In the synthesis of n-altrose from D-ribose, first effected by Levene and Jacobs, the only crystalline intermediate was the characteristic calcium D-altronate -3.5 H2O. The sirupy lactone prepared from it was then reduced to n-altrose with sodium amalgam, as mentioned earlier in this review. Calcium n-altronate has been obtained from other sources also, such as the aluminum chloride rearrangement of the acetates of lactose, cellobiose and glucose and subsequent transformation of the neolactose, celtrobiose and altrose derivatives thus produced (see Section... 

Octa-O-acetylcellobiose can, likewise, be rearranged by the action of corresponding excesses of aluminum trichloride and phosphorus pentachloride, and thereby gives the heptaacetate of 4-0-j3-d-glucopyranosyl-a-D-altropyranosyl chloride in 40-45% yield. Again, inversion at C-2 and C-3 of the reducing residue is observed. The formation of D-mannose and D-altrose derivatives is observed when penta-O-acetyl-D-glucopyranose is treated with aluminum trichloride-phosphorus pentachloride. ... 

The late George J. Robertson and his collaborators have developed a very useful method of transforming glucose derivatives into altrose derivatives. In 1933, Mathers and Robertson, in a projected synthesis of 4,6-dimethyl-D-glucose, attempted to remove the tosyl (p-toluene-sulfonyl) groups from methyl 2,3-ditosyl-4,6-dimethyl-a-D-glucoside. The hydrolysis of this compound with alcoholic alkali followed an unexpected course. One product was an anhydro derivative of a methyl di-methylhexoside the other product likewise was not the expected methyl... 

The alkenes (23) and (2 4) have been prepared from the D-altrose derivative (25) (see Chapter 111), and the enol ether (26) was the product formed by treatment of the corresponding D-talose... 

Methyl 3-chloro-3-deoxy-allo8ide Allose dithioacetal Altrose Derivatives Altrose... 

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... 

The S,6-dithio-glucosyl donor 17 was synthesized in eight conventional reaction steps from tri-O-acetyl-D-glucal and converted in six further standard steps to the cyanobacterial sulfoUpid 18. By reaction with the corresponding alcohols under Lewis acid catalysis, the 2,6-anhydro-2 thio-D-altrose derivative 19 has been converted, almost quantitatively, to alkyl glycosides 20 which on desulfuration should give easy access to alkyl 2,6-dideoxy-P-D-r/b< -hexopyranosides. ... 

When educt 150 is kept in DMF or methanol (the latter containing 1 % HCl), it gives an 8 2 reaction, either with the solvent or chloride, with formation of a 2-0-formyl- and 2-chloro-2-deoxy-D-altrose derivative, respectively. 

It has been recently shown [11] that a Swern oxidation followed by an intramolecular Tischenko reaction gives access to L-idose or L-altrose derivatives from the corresponding protected hexos-5-uloses. As can be seen from Scheme 6, D-glucitol 14 was oxidised to aldulose 15 via a Swern oxidation. Subsequently, this compound was treated with a trivalent samarium reagent (tert-BuOSml2), thereby inducing a Tischenko reaction, which led to L-fdo-configured ferf-butyl... 

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