Carbonic acid derivatives, cyclic

Most important are quantitative solid-state reactions of cyclic carbonic acid derivatives with gaseous or solid amines. These give open-chain amides that can be recyclized in various cases to new products of preparative interest. 

Phosgene is reported to combine with a wide range of oxygenated materials, including alcohols, ethers, ketones, carboxylic acids, anhydrides, lactones, esters, carbonic acid derivatives, etc. Only the reactions of COCIF with alcohols, phenols and cyclic ethers have been reported, resulting usually in the generation of fluoroformates. Such materials can often be usefully converted into the corresponding fluoro compound by means of decarboxylation in the presence of BF3, EtjO, pyridine, or other materials. 

Scheme 11.3 Lipase-catalyzed polymerization of L-tartaric acid derive cyclic carbonate followed by deprotection of the ketal groups to give chiral, hydroxy functional polycarbonate.

Cyclic carbonic acid derivatives, useful as copolymerization components for the preparation of polycarbonates, are obtained by treating a polyol such as a trime-thylolalkane (e.g. trimethylolpropane) with a carbonic add derivative such as a dialkyl carbonate (e.g. diethyl carbonate). They can be copolymerized with other organic carbonates at 150-240 °C and 0.001-10 mbar to give insoluble, cross-linked polycarbonates, which can be depolymerized at 240-320 °C and 0.001-2 mbar [287]. 

Five- or six-membered saturated cyclic ketones can also react by another pathway that does not involve decarbonylation. In these reactions, the biradical initially formed by a-cleavage undergoes internal disproportionation without loss of carbon monoxide, resulting in the formation of either an unsaturated aldehyde or a ketene. Methanol is usually added to convert the reactive ketene to a stable carboxylic-acid derivative (Scheme 9.2). 

The HC1 generated in this reaction destroys one equivalent of diazomethane. This can be avoided by including a base, such as triethylamine, to neutralize the acid.74 Cyclic z-diazoketones, which are not available from acyl chlorides, can be prepared by reaction of an enolate equivalent with a sulfonyl azide. This reaction is called diazo transfer 5 Various arenesulfonyl azides76 and methanesulfonyl azide77 are used most frequently. Several types of compounds can act as the carbon nucleophile. These include the anion of the hydroxymethylene derivative of the ketone78 or the dialkylaminomethylene derivative of... 

The condensation of 1,4-diamines with a variety of carboxylic acid derivatives, e.g. imidate esters, orthoformic esters, /V-ethoxycarbonylthioamides (77JOC2530), nitriles and ethoxyacetylene, produces the cyclic amidine linkage —N = C(R)NH— (67AHC(8)2l, p. 40). Cyclic ureas, —NHC(0)NH—, have been similarly produced using carbonyl chloride, A, A -carbonyldi imidazole, carbon monoxide, thiocarbonyl chloride or carbon disulfide (67AHC(8)21, p. 38). 

The synthesis of succinic acid derivatives, /3-alkoxy esters, and a,j3-unsaturated esters from olefins by palladium catalyzed carbonylation reactions in alcohol have been reported (24, 25, 26, 27), but full experimental details of the syntheses are incomplete and in most cases the yields of yS-alkoxy ester and diester products are low. A similar reaction employing stoichiometric amounts of palladium (II) has also been reported (28). In order to explore the scope of this reaction for the syntheses of yS-alkoxy esters and succinic acid derivatives, representative cyclic and acyclic olefins were carbonylated under these same conditions (Table I). The reactions were carried out in methanol at room temperature using catalytic amounts of palladium (II) chloride and stoichiometric amounts of copper (II) chloride under 2 atm of carbon monoxide. The methoxypalladation reaction of 1-pentene affords a good conversion (55% ) of olefin to methyl 3-methoxyhexanoate, the product of Markov-nikov addition. In the carbonylation of other 1-olefins, f3-methoxy methyl esters were obtained in high yields however, substitution of a methyl group on the double bond reduced the yield of ester markedly. For example, the carbonylation of 2-methyl-l-butene afforded < 10% yield of methyl 3-methyl-3-methoxypentanoate. This suggests that unsubstituted 1-olefins may be preferentially carbonylated in the presence of substituted 1-olefins or internal olefins. The reactivities of the olefins fall in the order RCH =CHo ]> ci -RCH=CHR > trans-RCH =CHR >... 

A study of the mono- vs di-alkylation reactions of dibromide (9) with carbanions (lOc-g), covering a range of >15 pK units in DMSO, has revealed that the carbanions (lOd-g) derived from the less acidic carbon acids give exclusively the bis(monoalkylated) product (ii) however, carbanions (lOa-c) give the cyclic product (12) of dialkylation.21 This dichotomy is apparently a consequence of the relative rates of formation (by proton transfer, /id) and cyclization (kc) of die conjugate base of the monoalkylated intermediate. 

The boron atom dominates the reactivity of the boracyclic compounds because of its inherent Lewis acidity. Consequently, there have been very few reports on the reactivity of substituents attached to the ring carbon atoms in the five-membered boronated cyclic systems. Singaram and co-workers developed a novel catalyst 31 based on dicarboxylic acid derivative of 1,3,2-dioxaborolane for the asymmetric reduction of prochiral ketones 32. This catalyst reduces a wide variety of ketones enantioselectively in the presence of a co-reductant such as LiBH4. The mechanism involves the coordination of ketone 32 with the chiral boronate 31 and the conjugation of borohydride with carboxylic acid to furnish the chiral borohydride complex 34. Subsequent transfer of hydride from the least hindered face of the ketone yields the corresponding alcohol 35 in high ee (Scheme 3) <20060PD949>. 

The preparation of a cubic phase with supramolecular chirality was achieved using a branched folic acid derivative incorporating glutamic acid residues (Fig. 11) as the source of chirality [93]. The pterin rings of folic acid residues are able to form a cyclic tetramer as a result of two hydrogen bonds between the components. Depending on the number of carbon atoms in the alkyl substituents, the compounds form columnar phases over a wide temperature range, and for 8 and 9 form cubic phases at temperatures above 130 °C. Addition of sodium triflate stabilises the cubic phase for 7, and the salt is incorporated into the other mesophases. It was implied that the cation resides between stacked tetramers. Supramolecular chirality is expressed for both the columnar and the cubic phases, as revealed by vari-... 

Using this method, several mesogen diacetylenes were obtained [49]. Palladium-catalysed coupling of an allylic cyclic carbonate with 1-pentynyl phenyliodonium tetrafluoroborate to give an enyne was highly successful [50]. Alkynyl iodonium triflates and lithium salts of diethyl 2-[(diphenylmethylene)amino]malonate were used for the preparation of alkynyl-a-amino acid derivatives, e.g. [51] ... 

The mixed esters of carbonic acid [see Table I, type (a)] were formerly designated carboalkyloxy, but this term is now avoided, since it was often confused with carboxyalkyl [—(CHj) —CO2H]. A, the mixed esters of dithiocarbonic acid [see Table I (e) R = alkyl] have been termed alkyl xanthogenates or alkyl xanthates, thus relating them to the corresponding acid dithiocarbonates (R = metal), industrially called xanthates, but more precisely termed 0-(/Si-metal thiolthiocarbonyl) derivatives. Of the mixed-ester types and acid types indicated in Table I, examples of (a), (b), (e), (f), and (g) of the former, and (a), (b), and (e) of the latter have so far been reported. For intermolecular esters, examples of (i) and (k), and, for cyclic esters, examples of (0) and (t), have been described. 

An interesting preparation of 128 involves the cycloaddition of carbon suboxide to the anil of cyclopentanone (129).87 Compound 129 also reacts with monosubstituted malonyl chlorides to give iV-aryl-2-oxo-3-alkyl-4-hydroxy-6,7-dihydro-5ff-1 -pyrindines (131) in fair yields.88 Similarly, the oxime ether of cyclopentanone (132) reacts to give the cyclic hydroxamic acid derivative (133),89 and benzylmalonyl chloride reacts with the A,A-dimethylhydrazone of cyclopentanone (134a) to give 134b in 90% yield.90... 

However, in the reaction of glutaric acid derivatives with CF3CONH2 in the presence of EDC hydrochloride/HOBt, cyclic imides are obtained in yields of 58-92 DCC promotes the facile formation of organic carbonates from aliphatic alcohols and carbon dioxide at 310°K and moderate pressure." " ... 

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