Diols cyclic carbonates

The by-product is the water-soluble imidazole. The reaction proceeds in high yield in the case of m-1,2-diols. Cyclic carbonates of trans-1,2-diols are formed in much lower yields. 

A soln. of benz[a]anthracene in 10 moles vinylene carbonate refluxed 18 hrs. under Ng at ca. 175-180° 7,12-dihydro-7,12-ethanobenz[a]anthracene-13,14-diol cyclic carbonate. Y 80%.-This is the first step of a high-yield multi-step synthesis of 7,12-dimethylbenz[a]anthracenes from benz[a]anthracenes. F. e. s. M. S. Newman and Zia Ud Din, J. Org. Chem. 36, 966 (1971) diene synthesis with anthracenes s. a. D. M. McKinnon and J. Y. Wong, Can. J. Chem. 49, 3178 (1971) synthesis of dibenzobarrelenes s. H. P. Figeys and A. Dralantis, Tetrahedron 28, 3031 (1972). 

Pd(0)-catalyzed arylation of the aryl-substituted a-allenic alcohols with hypervalent iodonium salts afforded substituted trans-epoxides. Alternatively, arylation of the alkyl-substituted a-allenic alcohols in the presence of K2CO3 afforded syn-diol cyclic carbonates and trans-epoxides in the presence of CS2CO3 (Scheme 5). 

Treatment of cyclic carbonates of 1,2-diols with thiocyanate ion at temperatures of 100 °C or higher yields thiiranes (Scheme 145) (66CRV297, 75RCR138). Thiourea cannot replace thiocyanate satisfactorily, and yields decrease as the carbonate becomes more sterically hindered. The reaction mechanism is similar to the reaction of oxiranes with thiocyanate (Scheme 139). As Scheme 145 shows, chiral thiiranes can be derived from chiral 1,2-diols (77T999, 75MI50600). 

The thietanes are most often prepared through ring closure of 1,3-dibromides or 1,3-disulfonate esters1930 239,240, through fusion of cyclic carbonate esters of 1,3-diols with... 

A novel chemoenzymatic route to polyester polyurethanes was developed without employing highly toxic isocyanate intermediates. First, diurethane diols were prepared from cyclic carbonates and primary diamines, which were subsequently polymerized with dicarboxylic acids and glycols by using lipase CA as catalyst, yielding the polyurethanes under mild reaction conditions. 

Cyclic carbonate esters are easily prepared from 1,2- and 1,3-diols. These are commonly prepared by reaction with A.A -carbonyldiimidazole214 or by transesterification with diethyl carbonate. 

Cyclic carbonic esters can be readily obtained from 1,2-diols and CDI.[242H254] Apart from the observed high yields, the procedure is so straightforward that it undoubtedly constitutes the method of choice for compounds of this type. The procedure offers the advantages of mildness, simplicity, and absence of by-products other than imidazole,... 

The best procedure for obtaining a cyclic carbonic ester requires that CDI (4 equiv.) be added gradually over a period of ca. eight hours during refluxing of the reaction mixture. However, it was found in the case of cw-cyclohexane diol that if the diol and CDI are dissolved together in benzene and the solution heated under reflux, the bis(imidazole-iV-carboxylate) is obtained instead of the cyclic carbonic ester. 4 ... 

A cyclic carbonate was utilized as a protecting group for the cw-diol system in butane-1,2,4-triol ... 

The five-membered 1,2-cyclic carbonate was isolated as the only product (regio-selective protection of the vicinal diol system).[255J Analogous formation of a cyclic carbonate containing a secondary hydroxy group is described in reference [256]. 

Table 3-13. Cyclic carbonic esters obtained by the reaction of 1,2-diols with CDI.

Hydrogenation of carbon dioxide in the presence of an epoxide generates a mixture of the diol, its formate esters, and the cyclic carbonate. While the reaction has been shown to operate in high yield (1300 TON for the cyclic carbonate Eq. (10)) [93], the fact that a mixture is generated and that the cyclic carbonate could be made more cleanly in the absence of H2 makes the reaction uninteresting for synthesis. Sasaki s group showed that this reaction in the presence of an amine base gives CO rather than cyclic carbonate (Eq. (11)) [94]. The epoxide then serves as a trap for the water. 

It seems reasonable that polyester cyclics could be prepared by an extension of the /wendo-high-dilution [17] chemistry used for the preparation of cyclic carbonate oligomers [18, 19] however, such proved not to be the case. Brunelle et al. showed that the reaction of terephthaloyl chloride (TPC) with diols such as 1,4-butanediol did not occur quickly enough to prevent concentration of acid chlorides from building up during condensation [14]. Even slow addition of equimolar amounts of TPC and butanediol to an amine base (triethylamine, pyridine or dimethylaminopyridine) under anhydrous conditions did not form cyclic oligomers. (The products were identified by comparison to authentic materials isolated from commercial PBT by the method of Wick and Zeitler [9].)... 

Cyclic thionocarbonates are formed under soliddiquid phase-transfer catalysed conditions from the reaction of diols with carbon disulphide [63]. The reaction has been specifically described for the reaction of carbohydrates, but should be generally applicable to all diols. 

D) Synthesis of ABC ring system In order to prepare the molecule for closure of the 8-membered B ring, diol 22 was converted to its cyclic carbonate by treatment with phosgene in the presence of KH. 

Cyclic carbonates are not commercially available and have to be synthesized prior to use. As a result, commercially available carbonates such as diethyl carbonate [55-57] or diphenyl carbonate [93] were evaluated in polycondensation reactions with diols to prepare polycarbonates since they allow a broader spectrum of polymers to be accessed. Unfortunately, polymerizations employing diethyl carbonate require the use of an excess diethyl carbonate [55]. Nevertheless, polymers with molecular weight of 40kDa were achieved within 16 h. Also, the polymerization of diphenyl carbonate with butane-1,4-diol or hexane-1,6-diol via the formation of a cyclic dimer produced polymers with molecular weights ranging from 119 to 339kDa [93]. 

A rapid one-pot method for converting 1,3-diols into oxetanes by the intramolecular Williamson reaction has recently been described. The monolithium salt is generated by treatment of the diol with one equivalent of butyllithium in cold THF, followed by addition of one equivalent of tosyl chloride to give a monotosylate, which is cyclized by addition of a second equivalent of butyllithium (equation 83). Yields of 70-90% are reported for a variety of alkyl- and aryl-substituted oxetanes (81S550). Another simple method for converting 1,3-diols into oxetanes consists of converting them to cyclic carbonate esters by ester... 

Cyclic carbonates are made by treating 1,2-diols with dialkyl carbonates using an alkyl ammonium and tertiary amine catalyst. The combination of propylene glycol and dimethyl carbonate has been reported to result in a 98% yield of propylene carbonate (21). 

Pyrolytic decomposition of cyclic carbonate eaten of 1,2-diols hjus been utilized on occasion for epoxide synthesis. Ethylene Oxide jiml glycidol, for example, have been prepared26 mc from ethylene carbonate and glyceryl carbonate respectively (Eq. 314). 

Cyclic carbonates can be produced from diols and C02 in the presence of suitable catalysts (Equation 7.24). 

Freshly prepared sodium methoxide (0.1 ml of a 1 M solution in methanol, 10 mmol) was added dropwise to a solution of cis-3,5-cyclohexadiene-l,2-diol (112 mg, 1 mmol) in dimethyl carbonate (1.7 ml) and methanol (0.2 ml) at RT under argon, and stirred for 20 min. A small aliquot was removed, solvent evaporated in vacuum (bath T 22°C) and the resulting solid was washed with a small volume of chilled (-20°C) ether and chilled (-20°C) petrol (b.p. 30°-40°C) to afford the 3a,7a-dihydrobenzo[l,3]dioxol-2-one (cyclic carbonate) as a beige-coloured solid, mp 90°C (dec.). 

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