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Synthesis diol compounds

Thus, it is possible to use this reaction to obtain new macromolecules (di-ols or diamines) with low glass-transition temperature (Tg) and no crystalline phase. Earlier works suggested the synthesis of hydroxy-telechelic oligomers by radical addition of thiol onto dienes. But, the products obtained showed poor solubility in organic solvents and a high melting point. Our process, however, improves the properties of diol compounds (better solubility and decrease of the melting point). [Pg.39]

To investigate their possible occurrence in plants, we have developed convenient methods for the synthesis of 24-epiteasterone (71) and 24-epityphasterol (75) as well as their corresponding B-homo lactones 43 and 42, respectively (Scheme 9). For the synthesis of compound 71 the (24f )-3p-hydroxy-6-ketone 68 was used. Asymmetric catalytic dihydroxylation of the A22 double bond of 68 gave the (22/ ,23/f)-diol 71 as the main product, besides traces of its (22S,23S)-epimer. Baeyer-Villiger oxidation of 71 with CF3CO3H led to a 1 0.6 mixture of 2-deoxy-3,24-diepi brassinolide (43) and its 5a-oxa-6-oxo isomer 72, which were separated by preparative HPLC. [Pg.515]

Whiting needed acetal (45) in his synthesis of compounds from the heartwood of conifers. Disconnection of the acetal gives diol (46) which can be made from enone (47), This leads into the Mannich routine and hence to the Friedel-Crafts product (48),... [Pg.165]

Mesitylate esters are common intermediates in chemical synthesis and are very unstable. In order to monitor the extent of a reaction, it is often necessary to monitor all reaction species the precursor, mesylate intermediates, and end products. The mesylation reaction of 3-(2-isopropylphenyl)-l-hydroxy-1-R-propane (where R is a bulky chlorinated hydrocarbon) was followed on a diol column (A = 320 nm) using a 15-min 15/85 5/95 (75/25 hexane/toluene)/ethyl acetate gradient [883]. Intramolecular ring closure of the analyte occurred on the silica support at room temperature. Chromatography yielded a large, tailed cyclic ether peak followed by the mesylated material followed by the unieacted diol compound. Elution was complete in 14 min. The silica-facilitated reaction was greatly reduced when the system temperature was taken down to 10°C and was prevented when the system tenqterature was -30°C. [Pg.328]

The controlled synthesis of discotic polymers requires a functionalized tristar-discogen-monomer. The described reaction of 3,4,5-tris(alkoxy)benzoic acid chloride with protected cis,cis-phloroglucit and the subsequent deprotection leads to a first key-compound in this synthetic pathway the diol-compound 4, member of a novel class of discotic associates. A controlled functionalization of the 3,4,5-tris(alkoxy)derivatives should lead to the second key-compound in the stepwise synthesis of discotic polymers. [Pg.350]

Takami K, Matsuno R, Ishihara K. Synthesis of polyurethanes by polyaddition using diol compounds with methacrylate-derived functional groups. Polymer 2011 52(24) 5445-51. [Pg.346]

The synthesis of insect sex attractants using a polymeric support essentially involves the principle of monoprotection of diols by trityl ether. From the polymer-bound diols, the synthesis of compounds of general formula AcO(CH2) —CH==CH—CHj) CH3 has been achieved (Leznoff and Fyles, 1976 Leznoff et al., 1977 Fyles et al., 1978) via three different routes (Scheme 9-10). [Pg.148]

To illustrate how aldol condensation may be coupled to functional group modifi cation consider the synthesis of 2 ethyl 1 3 hexanediol a compound used as an insect repellent This 1 3 diol is prepared by reduction of the aldol addition product of butanal... [Pg.773]

A second approach for the synthesis of 6-formylpterin (23) involves the condensation of triamin opyrimidinone (10) with 5-deoxy-L-arabinose (26). The key diol is obtained in four steps starting from compound (10). Cleavage of the diol side chain is achieved either with periodate (39) or with lead(TV) (40) to furnish 6-formylpterin (23) in 45% overall yield. [Pg.39]

The same mixture of H and I was obtained starting with either of the geometrically isomeric radical precursors E or F. A possible explanation is based on the assumption of a common radical conformer G, stabilized in the geometry shown by electron delocalization involving the radicaloid p-orbital, the p-peroxy oxygen and Jt of the diene unit. The structure of the compounds H and I were determined by H NMR spectra and the conversion of H to diol J, a known intermediate for the synthesis of prostaglandins. [Pg.298]

Stoddart and his coworkers have reported syntheses of the trans-syn-trans and the trans-anti-trans isomers of dicyclohexano-18-crown-6 The synthesis of these two compounds from trans-l,2-cyclohexanediol was accomplished in two stages. First, the diols were temporarily linked on one side by formation of the formal, and this was treated with diethylene glycol ditosylate and sodium hydride to form the hemi-crown formal. Removal of the formal protecting group, followed by a second cychzation completed the synthesis. The synthesis of the trans-anti-trans compound is illustrated below m Eq (3 12) and the structures of the five possible stereoisomers are shown as structures 1—5. [Pg.25]

Although the first all-sulfur macrocycles were prepared many years ago " the first systematic study of such compounds was initiated by Busch and his coworkers , who were interested in the cation binding properties of such ligands. A sequential synthesis was utilized to produce 1,4,8,11-tetrathiacyclotetradecane [tetrathia-14-crown-4 (70)] . In the first step, 1,3-propanedithiol is metallated using sodium and alkylated with 2-chloroethanol. The diol was then treated with thiourea to form the dimercapto-dithioether compound 9. The latter was once again metallated with sodium and allowed to react with 1,3-dibromopropane. The yield of 70 in the ring closure step, conducted at high dilution in absolute ethanol, was 7.5% after recrystallization. The entire sequence is illustrated in Eq. (6.8) . ... [Pg.270]

Acetoxy-21-nor-5a-cholestan-20-one (73a) as well as the free alcohol (73b) react with methylmagnesium iodide to give a mixture of epimeric diols (74). After treatment with acetic anhydride and subsequent hydrogenation over reduced platinum oxide this mixture alfords 3j5-acetoxy-5oc-cholestane (75) which is identical with the natural product. This synthesis has been used to prepare the 21- C compound (75) in a total yield of 18... [Pg.70]

A variant of the Williamson ether synthesis uses thallium alkoxides. The higher reactivity of these can be of advantage in the synthesis of ethers from diols, triols and hydroxy carboxylic acids, as well as from secondary and tertiary alcohols on the other hand however thallium compounds are highly toxic. [Pg.293]

The reactions of olefins with peracids to form epoxides allows for the selective oxidation of carbon-carbon double bonds in the presence of other functional groups which may be subject to oxidation (for example, hydroxyl groups). The epoxides that result are easily cleaved by strong acids to diols or half-esters of diols and are therefore useful intermediates in the synthesis of polyfunctional compounds. [Pg.8]

The carboxyl terminated ACPA, 4,4 -azobis-(4-cya-nopentanoic acid), turned out to be a suitable reagent in condensation reactions. This compound can be prepared by Strecker s synthesis from levulinic acid following the method of Haines and Waters [12]. Regarding the formation of polymeric azo initiators, Matsakuwa et al. [13] reported on the condensation of ACPA with various diols and diamines in the presence of a condensation agent, I-methyl-2-chlorpyridinium iodide, and a cata-... [Pg.737]

The synthesis of the right-wing sector, compound 4, commences with the prochiral diol 26 (see Scheme 4). The latter substance is known and can be conveniently prepared in two steps from diethyl malonate via C-allylation, followed by reduction of the two ethoxy-carbonyl functions. Exposure of 26 to benzaldehyde and a catalytic amount of camphorsulfonic acid (CSA) under dehydrating conditions accomplishes the simultaneous protection of both hydroxyl groups in the form of a benzylidene acetal (see intermediate 32, Scheme 4). Interestingly, when benzylidene acetal 32 is treated with lithium aluminum hydride and aluminum trichloride (1 4) in ether at 25 °C, a Lewis acid induced reduction takes place to give... [Pg.197]


See other pages where Synthesis diol compounds is mentioned: [Pg.441]    [Pg.288]    [Pg.288]    [Pg.1035]    [Pg.252]    [Pg.176]    [Pg.58]    [Pg.88]    [Pg.53]    [Pg.189]    [Pg.709]    [Pg.208]    [Pg.545]    [Pg.159]    [Pg.434]    [Pg.439]    [Pg.626]    [Pg.25]    [Pg.30]    [Pg.232]    [Pg.201]    [Pg.299]    [Pg.174]    [Pg.303]    [Pg.310]    [Pg.431]    [Pg.556]    [Pg.657]    [Pg.676]    [Pg.781]   
See also in sourсe #XX -- [ Pg.61 ]




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