O-Diols

Preparative scale synthesis of P-D-glucopyranoside using secondary alcohols and l,o)-diols (under kinetic condtion)... 

Halogens are frequently used as oxidation agents and, under two-phase conditions, they can either be employed as ammonium complex halide salts [3], or in the molecular state with or without an added quaternary ammonium catalyst [4]. Stoichiometric amounts of tetra-n-butylammonium tribromide under pH controlled conditions oxidize primary alcohols and low-molecular-weight alkyl ethers to esters, a,cyclic ethers produce lactones [3], and secondary alcohols yield ketones. Benzoins are oxidized to the corresponding benzils (80-90%) by the tribromide salts in acetonitrile in the presence of benzoyl peroxide [5]. 

Dioxygenases that open the aromatic ring in the vicinal position to the o-diols are called extradiol dioxygenases. A mononuclear Fe(II) or Mn(II) complex forms their active site. This is, for instance, the case of 2,3-dihydroxybiphenyl-1,2-dioxygenase of Pseudomonas sp. Strain KKS102, the square pyramidal geometry of which is schematized in Figure 3.3... 

Eu s planar chiral ferrocenyl 4-DMAP catalyst 16 was also shown to be effective for the ASD of mei o-diols as illustrated for the case of unusual meso-diol 22 (Scheme 9) [81]. 

In addition, Oriyama was the first to provide a practical protocol for the ASD of mei( -l,2-diols [179-182], Thus, employing just 0.5 mol% of (5)-proline-derived chiral diamine 56 in conjunction with benzoyl chloride as the stoichiometric acyl donor in the presence of EtjN, asymmetric benzoylation of a variety of me o-diols could be achieved with good to excellent enantioselectivities (66-96% ee) and 80% yields (Scheme 24) [179-182],... 

All of the isophthalate-based polyether-ester copolymers which were prepared using various diols are slow to crystallize. Those copolymers that eventually do crystallize exhibit excellent tensile strength and tear strength. All of the 2,6-naphthalenedicarboxylate copolymers prepared using linear ,o>-diols exhibit excellent tensile strength and tear strength. Phase separation in the melt is encountered with 4,4 -biphenyldicarboxyl-ate-based copolymer at the 50-wt % ester level when 1,4-butanediol is used as the diol monomer but not when 1,3-propanediol, 1,5-pentanediol, and 1,6-hexanediol are used. 

Palladium acetate with bromobenzene as cooxidant will oxidize primary a,o>-diols (27 equation 27) and (28 equation 28) to lactones, but as can be seen from the examples given, the selectivity in unsym-metrical cases is rather low. ... 

Historically, the first supported oxidizing reagent, reported by Fdtizon and Golfier, was silver carbonate on celite (another diatomaceous earth). This was obtained by precipitation of the reagent onto its support. Ag2C03 on celite smoothly oxidizes primary and secondary alcohols, a,(o-diols, hydroquinones and amines. The main practical asset of the reagent is that it avoids the need to filter off finely divided silver salts after reaction. 

Diphenyl- IV/ld, 410 2-(4-Formyl-phenyl)-l,3-dioxolan-4-yl-methoxy - polymergebun-den E14a/1, 242 (Polym.-o-Diol + Dial)... 

The asymmetric transesterification of cyclic me o-diols, usually with vinyl acetate as an irreversible acyl transfer agent, includes monocyclic cycloalkene diol derivatives, bicyclic diols, such as the ej o-acetonide in eq 12, bicyclic diols of the norbomyl type, andorganometallic l,2-bis(hydroxymethyl)ferrocenepossessing planar chirality. 

Asymmetric Acylation of me o-Diols. Both cyclic and acyclic me o-1,2-diols are desymmetrized by acylation in the presence of a stoichiometric amount of this ligand with modest-to-excellent enantioselectivity (eq 4). In a special case, cis-5,5-dimethyl-2-cyclopentene-l,4-dior was monobenzoylated in the presence of a catalytic amount of this ligand in good yield and with perfect enantioselection (87%, >99.5% ee). 

Oxidations catalyzed by NAD(P) -dependent dehydrogenases formation of chiral lactones from /nej o-diols stereoselective formation of ketones from polyfunctional alcohols regioselective oxidations of steroids. 

Figure 21. Electroenzymatic oxidation of w e o-diols to give enantiomerically pure lactones with horse liver alcohol dehydrogenase (HLADH) and PDMe" as redox catalysts at pH 7.8 and 150mV vs. Ag/AgCl reference [125].

The following data for the production of chiral y-lactones from me o-diols using the indirect electrochemical NAD" regeneration procedure can be given In a volume of 100 mL using 3.2 mg (1 x 10 mol) of PDMe, 70mg (1 x 10 mol)ofNAD, and 12.5mg(16U)of HLADH, after 20 h 99.5% of the meso-diol (0.5 to 1.0 g = 3.5 to 7.0 mmol) were converted to the enentiomerically pure lactone. Thus, the space-time yield can be calculated to be 6 to 12 g/L -day . The productivity is limited by the small amount of the enzyme. 

Ether linkages in open-chain bolaamphiphiles were obtained in a 20% isolated yield from a,o)-dibromoeicosane with an alcohol in THF containing sodium hydride (Scheme 2.8). The synthesis of macrocyclic tetraethers was unsuccessful. Attempts to reduce macrocyclic lactones with four ester groups via a variety of methods failed. The production of macrocyclic thioacetals from benzaldehyde derivatives and a,to-dithiols was unproblematic and produced quantitative yields (Scheme 2.8). The cyclization of 2,2-thiodiethanol with a,(o-diols in the melt and in the presence of /7-toluenesulfonic acid is an intermediate case. Apolar macrocycles were obtained in 50% yield. 5-(2-hydroxyethyl)thiiranium ions are presumably formed as reactive intermediates during the ether formation steps. The sulphur atom was oxidized to the... 

A similar two-phase procedure involves addition over 15 min. of the theoretical quantity of chromic acid (from Na2Cr207-2 HjO, H2SO4, and water) to a solution of the alcohol in ether. After 2 hrs. at 25-30° the ether layer is separated and the product isolated. Oxidation of (-menthol gave (-menthone in 97% yield with only a trace of d-isomenthone, whereas 3-4% of this isomer was present on oxidation with aqueous chromic acid (50-55°), H2Cr04 in 90% acetic acid (25°), or HjCrO,-acetone (5-10°), and the yields in these oxidations were 90, 71, and 86%. This procedure has been used for Ihc selective oxidation of steroidal l6/l,2()o-diols to l6-keto-20 -ols. ... 

F. INTRAMOLECULAR RING CLOSURE OF a,o>-DIOLS USING ORGANIC SULFONYL CHLORIDES (THE OKAHARA RING-CLOSURE REACTION)... 

C. INTRAMOLECULAR RING CLOSURE TO FORM A C—O—C LINKAGE FROM AN a,o)-DIOL OR AN w-HYDROXYlSOCYANATE... 

Oxidation of a,o>diols. In the field of organic synthesis, it is known that it is... 

Aeromax Astmerole Benzenedimethanol GR 33343X Salmeterol Salmeterolum Xylene-a,o -diol. Structural analog of albuterol. P2-Adrenergic agonist Ephedrine derivative. Used as a bronchodilator. Crystals, mp = 75.5-76,5°. Glaxo Labs. 

Under different reaction conditions, vicinal diol production [70] or C=C double bond oxidative cleavage to carboxylic acids occurs [59, 71], Dialdehydes are produced from cycloolefins, by tungstic acid as catalyst in t-butanol [72], Secondary alcohols yield ketones, while primary alcohols produce aldehydes or carboxylic acids [59, 68-69, 73-74], Different products are obtained from glycols, under different reaction conditions, 1,2-Diols are cleaved to ketocarboxylic acids and dicarboxylic acids [58, 75], or oxidised to a-hydroxy ketones [76], The latter can be obtained directly from the olefins, with lower selectivity [77], Lactones are formed by 1,4-diols and other a,o)-diols [78], Internal alkynes predominantly yield a,p-epoxyketones [79], or 1,2-diketones and carboxylic acids if HgfAcO) is added as the cocatalyst [80], Terminal alkynes yield a-ketoaldehydes and carboxylic acids. 

Resolution of cis-2-eyclohexene-1,4 diol. The reagent has been used for the synthesis of optically pure 6 from the me o-diol 2. Intermediates were purified... 

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