Dialdoses derivatives

Oxidation of 2 with methyl sulfoxide and boron trifluoride proceeds by conversion of the oxirane ring into an a-hydroxy aldehyde group, just as for simple oxiranes, giving198 the dialdose derivative 66. 

Other alternatives for chain extension have been developed. Wittig condensation between the dialdose derivative 194 and the (PPI13I) monosaccharide derivative 195 occurs with complete stereoselectivity, forming a cis linkage. Compound 196 is the precursor of a deaminotunicamine derivative.399... 

Reaction of several dialdose derivatives, for example 197, with furan or 2-methylfuran gave, in the presence of chloroacetic acid, condensation products with high stereoselectivity. The (S) configuration was assigned to the major diastereoisomer 198.401 The thiazole adduct (199) obtained from aldehyde 197 and 2-trimethylsilylthiazole can be converted to the 6-epimer (200) by an oxidation-reduction sequence (Scheme 20).402... 

The 1,5-dialdose derivative 201 has been chain-extended to the 1,6-dialdose derivative 202, by stereospecific addition of formaldehyde dimethylhydrazone, according to Scheme 21.403... 

A direct method for two-carbon sugar homologation of dialdoses leads to sugar /1-ketoesters. Thus, reaction of dialdose derivative 203 with ethyl diazoacetate in the presence of BF3 etherate alfords the /1-ketoester 204.404... 

In addition, its proton magnetic resonance spectrum unambiguously supported the 5-ketose structure (69). Rearrangements of epoxides to ketones when dicobalt octacarbonyl is used as the catalyst at temperatures above 100 , or when cobalt hydrocarbonyl is used at lower temperatures, are well known. By applying the technique of double irradiation to a sample of (68), the main component was shown to possess structure (68). Presumably, the free aldehyde group of the hydroformylation product immediately cyclized with the free hydroxyl group on C-3 to give the tricyclic structure (68). A third component (68a) (isolated in less than 5 % yield) was undoubtedly formed by subsequent reduction of the dialdose derivative (68). 

When 5,6-anhydro-l,2-0-isopropylidene-a-I>-glucofuianose (67) in ether was allowed to react with carbon monoxide (12 atmospheres, at room temperature) in the presence of sodium cobalt tetracarbonyl for 3 days, the stoichiometric amount of carbon monoxide was absorbed. The mixture was cooled to —5 , and subsequent treatment with methanol and iodine by the procedure of Heck and Breslow resulted in the formation (in 80 % yield) of the methyl uronate (70) and, in a yield of about 10%, the 6-deoxy-hexos-5-ulose (69). Reduction of the methyl uronate (70) and of the dialdose derivative (68) with lithium aluminum hydride yielded identical sugars. 

The reactions of allyltrialkylstannanes with dialdose derivatives proceed similarly, with a high di-astereofacial selectivity in 5.0 M LPDE via chelation-controlled catalysis by the lithium ion. For example, the galactose derivative (4) (1.0 M in ether) reacts with 1.5 equivalents of allyltri-n-butyltin in 5.0 M LPDE, giving rise after 1 h to 96% yield of 5 and 6 in a ratio 25 1, respectively (Scheme 6.3.3). Exposure of (4) to allyltrimethyltin in 5.0 M LPDE proceeded with a high diastereofacial selectivity >25 1. In contrast, treatment of (4) with allyltrimethyltin in 2.0 M LPDE at ambient temperature proceeded with reduced diastereofacial selectivity, giving rise to a 12 1 ratio of (5) and (6), respectively, in only 66% yield. 

Papadakis also prepared some condensation products from the dialdose derivatives 1,2-0-isopropylidene-a-D-xj/lo-pentodialdo-l, 4-furanose (7) and... 

The formation of higher-sugar dialdose derivatives by dimerization of terminal acetylenic sugars and polymerization of enosuloses is covered in Chapter 12. 

The glucofuranose diol 16 has been converted into hexo-l,6-dialdose derivative 17 by standard methodology, whereas the 1,5-dialdose 18 has been chain extended to the 1,6-dialdose derivative 19 (Scheme 1). Oxidation of some 5,6-dideoxy-hex-5-enofuranosides has afforded the corresponding 5-deoxy-hexo-l,6-dialdose derivatives. ... 

Further work has been reported on using sugars to elaborate chiral anthracyclines. The xylo-dialdose derivative (9) can be condensed with leuco-quinizarin leading to the derivative (10),which was then cyclized by the Marschlak procedure to the optically pure... 

A study on the Knoevenagel reaction of some aldehydo dialdose derivatives with pentane-2,4-dione revealed that acetyl transfer... 

The high pressure [4+21 cycloaddition of diene (13) to the dlaldose derivative (14) in the presence of Eu(fod)2 as catalyst gave largely the Isomer (15) (Scheme 4) the dialdose derivatives (16)... 

The Wittig reaction with dialdose derivatives has also been employed to synthesize polyols of long-chain hydrocarbons, as illustrated in Scheme 2 lyxose and xylose derivatives were similarly used to prepare stereoisomers which are relatives of naturally occurring plant products.- ... 

A synthesis of sinefungin has been described, using a nitro-aldol condensation between a dialdose derived from adenosine and an -nitro-aminoacid derivative to build the required Cj Q-carbon skeleton... 

Two separate syntheses of octosyl acid A (34) have been published both use dialdose derivatives to construct the carbon chain. In... 

Several alkynes related to compound (29) were prepared by treatment of the corresponding dialdose derivative with alkynyl Grignard reagents, and by reduction and oxidation processes they were converted into a series of octose derivatives, e.g. reduction gave 7,8-dideoxy compounds and oxidation alkynyl glycos-6-uloses. ... 

The D-galacto-dialdose derivative (19) has been used as a chiral... 

An improved synthesis of 5 -deoxy-5 -adenosine acetic acid (26) has been reported, utilizing the dialdose derivative (27) with a Wittig reagent. Similarly a dialdose derivative of ara-aden-osine has been used to make ara-5 -deoxy-5 -adenosine acetic acid via the ester (28), and also the corresponding acetamide and ethanol. 

The treatment of a dialdose derivative with lithiated methyl phenyl sulphone is discussed in chapter 11, and the preparation of a synthon of deazatunicamycin is covered in chapter 19. An improved synthesis of (6- C) aldohexoses from 1,2-Q-isopropvlidene-q-D-xylo-pentodialdo-l.4-furanose is included in chapter 2. The racemic synthesis of an aminosugar dialdose is mentioned in chapter 9. 

Imidazolidine and imidazoline derivatives were formed when dialdose derivatives reacted with 2,3-bis(hydroxylamino)-2,3-dimethylbutane (Scheme 60) oxidation of these derivatives afforded stable free radicals that were examined by e.s.r. spectroscopy. Several oxazole and thiazolidine derivatives having C-5 and C-6 of 3-0-benzyl-l,2-0-isopropylidene-jS-L-idofuranose as part of the heterocyclic ring, and a new class of bicyclic thiazolidine derivative (172) have been prepared by the reactions shown in Scheme 61. The bis(l,3,4-oxadia-zole) derivative (173) has been prepared by condensative cyclization of 2,3,4,5-tetra-O-acetylgalactaric acid bis(benzoylhydrazide) with triethyl orthoformate in p-dioxan. Other heterocyclic derivatives are referred to in Chapters 14 and 15. 

Theander s group has studied the reactions of several dialdose derivatives. Methyl a-D- / co-hexodialdo-l,5-pyranoside underwent -elimination and then conversion into the dienone (270) and the furan dicarboxaldehyde (271) on treatment with aqueous alkali (Scheme 103). The degradation of methyl a-o-... 

Carrying out the Kiliani reaction using H CN on the dialdose derivative (12) followed by hydrolysis to the labelled alduronic acid, reduction to the alcohol and hydrolysis with trifluoroacetic... 

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