Conduritol oxides

The conduritols (cyclohexenetetrols), and especially the conduritol oxides, are extremely versatile intermediates for the synthesis of cyclitols. As reviews are available, only recent work will be considered here. 

The reaction of bromoquercitols with sodium hydroxide may also be considered. The first 1,2-anhydroinositol ( conduritol oxide ) (116) was prepared by this method, and Nakajima and Kurihara have converted the bromoquercitol (11) into 1,2-anhydro-epf-inositol (7) in the same way. Epoxide migration may occur in the basic solution. ... 

The conduritol oxides are extremely valuable intermediates for synthesis. The great variety of addition reactions that they undergo includes direct... 

Finn KJ, Collins J, Hudlicky T (2006) Toluene Dioxygenase-Mediated Oxidation of Dibromobenzenes. Absolute Stereochemistry of New Metabolites and Synthesis of (-)-Conduritol E. Tetrahedron 62 7471... 

Ley SV, Redgrave AJ (1990) Microbial oxidation in synthesis concise preparation of (+)-conduritol F from benzene. Synlett 1990 393-394... 

The quasi-hydroxyl groups in the cyclohexenetetrols are even more readily oxidized catalytically. All six posable stereoisomers of the conduritols were carefully investigated with respect to their relative ease of catal3Ttic oxidation. Conduritol B (63b) has two equatorial hydroxyl groups on C-2 and C-3, and two quasi-equatorial hydroxyl groups on C-1 and C-4. Under these circumstances, conduritol B would not be expected to... 

On catalytic oxidation, conduritol C (66) gives (in just 10 min.) the ketone (66a), the quasi-equatorial hydroxyl group at C-1 (but neither the axial hydroxyl group at C-2 nor the quasi-equatorial hydroxyl group at C-4) being oxidized. The same ketone (66a) can also be prepared by oxidation of natural conduritol A (67). Both possible half-chair conformations of conduritol A (67) are equally stable, and hence there presumably exists an equilibrium in which the group at C-1, as well as that at C-4, is attacked and a racemate (66a) is produced. 

Conduritol E (68), having two quasi-axial hydroxyl groups gives, on catalytic oxidation, only the monoketone (69). Oxidation of both quasi-axial hydroxyl groups to the diketone does not, therefore, normally occur. Conduritol D (69a) gives, on catal3d ic oxidation, the readily crystallizable ketone (69b). 

Catalytic oxidation of all six conduritols has been studied. In each case, an allylic hydroxyl group was oxidized, regardless of the configuration or conformation, giving a trihydroxycyclohexenone (122). ... 

A detailed n.m.r. study of six isomeric conduritols (1,2,3,4-tetrahydroxycyclohex-5-enes) in deuterium oxide has shown that the conduritols also adopt a half-chair conformation (28). In order to... 

A one-pot variation of the thioether generation, applicable to the formation of cyclic sulfones, involves reaction of a dihalide (or halide equivalent) with a divalent sulfide, such as sodium sulfide. This methodology was used in the synthesis of conduritols, whereby sodium sulfide reacted with diepoxy stereoisomers 13 in a one-step thioether formation fScheme 8.5). The resulting thiapane isomers 14 were separated (HPLC) and then individually methylated and oxidized with m-CPBA to a set of isomeric sulfones, 15. 

The syntheas of conduritol E by a Sharpless dihydrox ation of 1,2-O-benzylidene-cis-qrcloh ca-3,5-diene-l,2-diol (made from benzene by microbial oxidation) has been reported together with a papa- correcting the original asssignments in reference. 13S. ... 

Considerable amount of v ork has been reported in the hydroxylation of aromatic rings. Thus, benzene on oxidation with Pseudomonas putida in presence of oxygen gives the cis-diol (Scheme 6). The cis-diol obtained could be converted by four steps into 1,2,3,4-tetrahydroxy compound, conduritol-and by five steps into the hexahydroxy compound, pinitol, an antidiabetic agent (Scheme 6)." ... 

The diolization of the double bond in this series of reactions appears to be analogous to the diolization of the double bond of conduritol, a cyclohexene-tetrol (see Cyclitol section). When the hexenetetrol above was oxidized directly, the hydroxyls entered cis to the hydroxyls already present and allitol was the chief product similarly, aHo-inositol was obtained on oxidation of o-isopropylideneconduritol diacetate with potassium permanganate. On the other hand, for the two fully acetylated tetrols (acyclic and cyclic), the hydroxyls entered trans to those already present, giving galactitol and mwco-inositol tetraacetate, respectively (p. 284). 

The configuration of conduritol, and incidentally those of aZZo-inositol, mwco-inositol, and dihydroconduritol, was elucidated in 1939 by Dangschat and Fischer (6 ), who applied the acetonation-oxidation technique previously used so successfully on quinic and shikimic acids. The steps utilized were as follows ... 

Z-Quinic acid was oxidized to benzoquinone by Wohler (101). Derivatives of conduritol and shikimic acid were hydroxylated at the double bond by Fischer and Dangschat (62, 85). 

Di-0-ter -butyldimethylsilyl-3,4-0-isopropylidene-D-glucitol on Swem oxidation then treatment with samarium diiodide gives the L-cA/ro-derivative 68 together with a small amount of the myo-isomer. Compound 68 was further converted into its hexaacetate for characterization purposes as well as into conduritol F tetraacetate. ... 

The microbial oxidation of benzene and its derivatives using Pseudomonas putida have been used in several cyclitol syntheses. These include the preparation of conduritol D and the deuterated compound 99", D-cA/ro-inositol and D-cAiro-3-inosose for which the key step involves a one pot oxidation-protection to an epoxy-acetonide derivative," " and racemic quebrachitol." Also reported are the syntheses of (+)-D-chrro-inositol, a//o-inositol, muco-inositol and neo-inositol from a halogenated conduritol epoxide." ... 

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