Diols and Derivatives

Another frequent PRS is the epoxy group, occurring at least once in 921 compounds (19%), while chlorohydrins, likely to have resulted from acid hydrolysis of the former, occur in 65 structures (the number of 1,2-diols and derivatives thereof is much higher but it is not possible to differentiate between such that result from hydrolysis of epoxides and which do not). Finally, a free aldehyde group, as another potential alkylant structure element occurs in 240 compounds (209 with a,P-unsaturated aldehyde group). 

The diastereoselectivity of the reduction of a-substiluted ketones has been the subject of much investigation. The reagent combination of trifluoroacetic acid and dimethylphenylsilane is an effective method for the synthesis of erythro isomers of 2-amino alcohols, 1,2-diols, and 3-hydroxyalkanoic acid derivatives.86,87,276,375 Quite often the selectivity for formation of the erythro isomer over the threo isomer of a given pair is >99 1. Examples where high erythro preference is found in the products are shown below (Eqs. 218-220).276 Similar but complementary results are obtained with R3SiH/TBAF, where the threo isomer product... 

Intramolecular Dieckmann cyclization of polystyrene-bound pimelates has been used to prepare (l-keto esters (Entry 4, Table 3.41). Oxidative cleavage reactions leading to the formation of aldehydes include the ozonolysis of resin-bound alkenes, the periodate-mediated cleavage of 1,2-diols, and the oxidation of Wang resin derived ethers (Entries 5-7, Table 3.41). 

H-bond interactions between the catalyst and substrate were suggested by Campbell to explain why his N-(4/-pyridinyl)-a-methylproline-derived catalysts 16 and 17 (Fig. 8.4) are more enantioselective for N-acylated 1,2-amino alcohols (s = 9-18.8) than for other classes of substrate [95-98]. Recently, Ishihara has designed the histidine derivative 34 as a minimal artificial acylase for the KR of mono-protected cis- 1,2-diols and N-acylated 1,2-amino alcohols [135]. This catalyst incorporates a sulfonamide linkage specifically to allow the NH group to engage as a H-bond donor with the substrates, and gives impressive levels of selectivity with a range of appropriate substrates (Scheme 8.16). 

Rings containing unsaturation may be synthesized from fragments in higher oxidation states. l,3-Dioxolan-2-ylium cations are obtained directly from tertiary 1,2-diols and acyl cations in excellent yields (80ZOR183). The reaction, shown in equation (37), is limited to tertiary alcohols since steric hinderance prevents nucleophilic ring opening by the counterion. Another synthesis of limited scope is the addition of monothiobenzils to diaryl-diazomethanes (equation 38). The reaction also works for the dicarbonyl derivatives. 

Cyanogen chloride has so far been reacted, always with very good yields, with a series of ethane-1,2-diols and ethane-1,2-dithiols, as well as with benzene-1,2-dithiol however, it has not yet been reacted with the simple ethylene-1,2-dithiol, which now offers further preparative possibilities in view of the new syntheses mentioned earlier. Similar 2-amino substituted 1,3-dithiolium derivatives have been synthesized by Sundholm and Smith starting from 2,3-dichloro-... 

The anodic oxidation of 1,2-diols and their ether derivatives is a simple and clean mediod for the fission of glycols to the corresponding carbonyl compounds (equation 1). The reaction is carried out using carbon electrodes in methanol containing tetraediylammonium p-toluenesulfonate as a supporting electrolyte.2 ... 

Some known odour and taint problems derived from polyurethane adhesives include the formation of cyclic 1,3-dioxolane and 1,3-dioxane structures from the reaction of 1,2-diols and 1,3-diols with aldehydes and ketones, and... 

Optically active 1,2-diol units are often observed in nature as carbohydrates, macrolides or polyethers, etc. Several excellent asymmetric dihydroxylation reactions of olefins using osmium tetroxide with chiral ligands have been developed to give the optically active 1,2-diol units with high enantioselectivities. However, there still remain some problems, for example, preparation of the optically active anti-1,2-diols and so on. The asymmetric aldol reaction of an enol silyl ether derived from a-benzyloxy thioester with aldehydes was developed in order to introduce two hydroxyl groups simultaneously with stereoselective carbon-carbon bond formation by using the chiral tin(II) Lewis acid. For example, various optically active anti-a,p-dihydroxy thioester derivatives are obtained in good yields with excellent diastereo-... 

There are a number of alternative methods for the synthesis of 1,2-diols and their derivatives that do not proceed via the coupling of two carbonyl groups. Ketyl radicals can be generated by the alkylative deoxygenation of carboxylic acids, and in the presence of TiCls coupled to give 1,2-diols (equation 111). However, yields are limited (22-33%) and complex product mixtures are often formed. 

Oxidation of an alkene by thallium(III) usually gives two products, a 1,2-diol and a single carbonyl compound (aldehyde or ketone), the combined yields of which were always virtually quantitative.However, oxidation of cyclobutene and 1-methylcyclobutene by thallium(III) perchlorate gave cyclopropanecarbaldehyde (3a) and acetylcyclopropane (3b) in 75-85 and 88-92% yield, exclusively cyclobutane-1,2-diol derivatives were not detected. ... 

Yet another demonstration of the versatility of epoxybutene comes from the asymmetric center, which has been converted into a number of four-carbon chiral synthons, such as 3-butene-1,2-diol and various derivatives, in >99% enantiomeric purity (20,21). 

Redox activity of bimetallic complexes based on tris(3,5-dimethylpyrazolyl)-borato molybdenum(II) and tungsten(II) nitrosyls. Complexes derived from ethane-1,2-diol and the crystal structure of anti [Mo(NO) HB(3,5-Me2C3HN2)3 -(0CH2CH20)]24CHCl3... 

Amphidinolide C (3a) is a 25-membered macrolide isolated from Amphidinium sp. (strain Y-5), possessing an s-cis and an s-trans Aienes, two fxo-methylenes, two tetrahydrofuran rings, a 1,2-diol, and four branched methyl groups. The relative stereochemistry of the C-l-C-8 and C-20-C-23 portions has been elucidated by NOESY correlations of amphidinolide C (3a) and its 7,8-0-isopropylidene derivative. Application ofthey-based configuration analysis revealed the etythro-m xion for the C-12-C-13 bond and the relation for the C-23—C-24 bond. The absolute... 

Dihydroxynaphthalene and 9,10-diacetoxyphenanthrene react with 1,2-diols and 1,2-dithiols in a one-pot synthesis of annulated 2,3-dihydro-1,4-dioxins and -1,4-dithiins (Scheme 26) <04TL1343>. The reaction of 2,3-dihydroxynaphthalene with 1,2-dihalogenated aromatic compounds leads to linearly annulated dioxins of particular interest are tri- and tetra-dioxins and various hetero-fused dioxins e.g. 62 (34%). Several examples yield cation radical salts on electrocrystallisation <04T8899>. Linear arrays of fused pyran-dioxin-cyclohexane rings as found in natural products derived from the milkweed family have been described e.g. 63 <04EJO4911>. 

The ionization constants of diphosphonic acid derivatives of amino acids, ethane-1,2-diol, and fluoro- and difluoro-methane have been determined, as well as those of the amide (107) and the monoester (108). ... 

The reactions of lithiophosphide reagents with alkyl halides or sulphonate esters have continued to find wide application in the synthesis of new phosphines. A series of phosphino-ethers, e.g., (22), has been prepared from the reactions of chloromethyl-substituted ethers with lithium diphenylphosphide. " A one-step synthesis of macrocyclic phosphino-ethers and -thioethers (23) is afforded by the reactions of dilithio-organophosphides with bis(j8-chloroethyl)-ethers and -thioethers derived from ethane-1,2-diol and ethane-1,2-dithiol, respectively. " A new family of water soluble phosphonio-phosphine ligands (24) has been prepared by the reaction of a,o)-dihaloalkanes with one mole of lithium diphenylphosphide, followed by quatemisation of the intermediate w-haloalkylphosphine with trimethylphosphine. The new ligand system (25) has been prepared by the reaction of chloromethylbenzene-chromium tricarbonyl with... 

Naemura, K. Ogasahara. K. Hirose, K. Tobe. Y. Preparation of homochiral azophenolic crown ethers containing l-phenylethane-1.2-diol and 2,4-dimethyl-3-oxapentane-l,5-diol as a chiral subunit Enantiomer recognition behaviour towards chiral 2-aminoetlianol derivatives. Tetrahedron Asymmetry 1997. 8 (1). 19-22. 

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