Cyclic anhydrides, preparation

Some of these compounds are used as potential intermediates for the preparation of 4,7-dioxo-4,5,6,7-tetrahydrothiazolo[4,5d]pyridazines (78). The diesters (77) are hydrolyzed under appropriate conditions to free acids (79), whose monopotassium salts (80) yield the cyclic anhydrides (81) under the influence of thionylchloride. Pyrolysis of 79, Rj = a-thienyl, results in its decarboxylation to 82. 

Cyclic anhydrides in which the ring is five- or six-rnembered are sometimes prepared by heating the conesponding dicarboxylic acids in an inert solvent ... 

Kost et al. studied the interaction of indole magnesium iodide with a number of cyclic anhydrides of dibasic organic acids.In addition to 254 the following. 3-indolyloxo acids were prepared in this manner -(3-indolyl)-8-oxovaleric acid (274), y-(3-indolyl)-y-oxocrotoiiic acid... 

In 1970, it was disclosed that it is possible to achieve the conversion of dimethylformamide cyclic acetals, prepared in one step from vicinal diols, into alkenes through thermolysis in the presence of acetic anhydride." In the context of 31, this two-step process performs admirably and furnishes the desired trans alkene 33 in an overall yield of 40 % from 29. In the event, when diol 31 is heated in the presence of V, V-dimethylforrnamide dimethyl acetal, cyclic dimethylformamide acetal 32 forms. When this substance is heated further in the presence of acetic anhydride, an elimination reaction takes place to give trans olefin 33. Although the mechanism for the elimination step was not established, it was demonstrated in the original report that acetic acid, yV, V-dimethylacetamide, and carbon dioxide are produced in addition to the alkene product."... 

Complete characterization of arylboronic acids is often difficult because they are readily transformed into stable cyclic anhydrides called boroxines5 and other polymeric species. Arylboronic acids are also known to be hygroscopic. Thus, arylboronic acids are often prepared and used directly as a mixture of different entities. Commercial arylboronic acids will very often contain varying amount of anhydrides. 

The scope of this reaction is similar to that of 10-21. Though anhydrides are somewhat less reactive than acyl halides, they are often used to prepare carboxylic esters. Acids, Lewis acids, and bases are often used as catalysts—most often, pyridine. Catalysis by pyridine is of the nucleophilic type (see 10-9). 4-(A,A-Dimethylamino)pyridine is a better catalyst than pyridine and can be used in cases where pyridine fails. " Nonbasic catalysts are cobalt(II) chloride " and TaCls—Si02. " Formic anhydride is not a stable compound but esters of formic acid can be prepared by treating alcohols " or phenols " with acetic-formic anhydride. Cyclic anhydrides give monoesterified dicarboxylic acids, for example,... 

Quinazolines, the benzo derivatives of pyrimidines, were prepared in a variety of ways, from methods analogous to those for synthesizing pyrimidines to vastly different condensation schemes. In analogous fashion to many pyrimidine preparations, Yang and coworkers reported the condensation of polymer-tethered amidines 109 with cyclic anhydrides 110 to yield a library of 2-amino-4(3//)-quinazoIinones 111 after cleavage from the resin <00TL7005>. 

The functionality of precursors varying between/ = 2 and/ = 6 is considered to be low (Figure 5.2). Polyurethane networks prepared from bifunctional telechelics and trifunctional triisocyanates, diepoxide (f = 2)-diamine (f = 4) systems, diepoxide if = 4)-cyclic anhydride (/ = 2) systems, phenol (/ = 3)-formalde-hyde if = 4) resins, or melamine (/ = 6)-formaldehyde (/ = 2) resins are in this category. 

Crosslinking of amine- or hydroxy-terminated PAMAM dendrimers using cyclic anhydride - amine or cyclic anhydride - hydroxy addition reactions was employed for preparation of crosslinked thin films of very low permeability [73], Polyanhydrides, such as maleic anhydride-methyl vinyl ether copolymers, were used as crosslinking components. In the case of amine-terminated PAMAM, crosslinking and chemical stability were further increased by imidization of the maleamic acid groups retro-Michael eliminations were followed by Michael additions to further crosslink the film. 

Scheme 10.11 Chemoenzymatic preparation of (-)-paroxetine using cyclic anhydrides in the enzymatic step.

In a similar manner to the preparation of 1,3,2-dioxathiolane 2-oxide from 1,2-dihydroxyethane and thionyl chloride, 1,2,3-oxadithiolane 2-oxide was prepared from 2-mercaptoethanol and thionyl choride <75ACS(A)414>. 1,2,5-Oxadithiolane 2,5-dioxide (66), the cyclic anhydride of ethane-1,2-disulfinic acid, was obtained by controlled hydrolysis of ethanebis(disulfinyl) chloride <76CRV747>. The corresponding 2,2,5,5-tetroxide (67) was obtained by treatment of ethane-1,2-disulfonic acid with thionyl chloride <(66HC(2l-i)l>. 

Spirolactones may also be prepared from cyclic anhydrides by the action of 1,5-bis(bromomagnesio)pentane (8lJOC309l>. The reaction proceeds through the keto acid... 

Important method for preparation of cyclic imides from cyclic anhydrides. 

This article summarizes and analyzes the results obtained for the anionic copolymerization of cyclic ethers with cyclic anhydrides. This reaction is of great practical importance, especially as curing reaction of epoxy resins and is also used for the preparation of linear polyesters with special functional pendant groups. 

Cyclic anhydrides of dibasic acids such as succinic or glutaric acid are readily prepared by dehydrating the acid with an excess of acetic anhydride, e.g. as in the preparation of succinic anhydride, Expt 5.141 cf. 3-nitrophthalic anhydride, Expt 6.162. 

The acid esters of 1,2-dicarboxylic acids are conveniently prepared by heating the corresponding cyclic anhydride with one molar proportion of the alcohol (see the preparation of alkyl hydrogen phthalates from phthalic anhydride and their use in the resolution of racemic alcohols, Section 5.19). 

Monoesters of symmetric dicarboxylic acids can be prepared either by monoesterification of a diacid [1] or by monosaponification of a diester. Dicarboxylic acids which can form five- or six-membered cyclic anhydrides are readily transformed into monoesters via these intermediates, but for diacids which cannot be converted into such cyclic anhydrides monosaponification of diesters seems to be more reliable than selective monoesterification. Monoesters or monoamides of succinic, maleic, glutaric, or related diacids can be rather unstable, because of the dose proximity of a carboxyl group (see Section 3.3). 

In starch chemistry and technology, extrusion is used for cooking as well as for preparation of starch complexes with such guest molecules as gluten6511 and lipids.651 Acylation of starch with cyclic anhydrides of dioic acids on extrusion has been demonstrated the reaction provides anionic starches.651... 

The selected example by Seneci et al. [51] reported the use of an IDA-DC [52] (iminoDiacetic acid based double cleavable) linker for structure determination and controlled release of pool libraries based on teicoplanin aglycone (TD) [53] and tested for their antimicrobial activities. The synthesis and the structure of the linker and the structure of teicoplanin aglycone are shown in Figure 9.15. Starting from iminodiacetic acid the linker was prepared in four trivial chemical steps (the cyclic anhydride used in step 4 was prepared in two steps from iminodiacetic acid) its structure was symmetrical with the amide arm bearing the carboxylic handle for the solid support attachment and the identical other arms bearing protected propylamine groups for the library synthesis. 

These tags were used to prepare the peptoid pool library L, (90 individuals, Figure 9.20). The aminoPS resin was acylated and split in nine aliquots (steps a, b), then a code from 3a-i was added to each aliquot (step c). A new acylation step was followed by alkylation with the amine monomer set M i (steps a, d) to give 5a-i. After pooling and splitting in aliquots (steps e and f), the cyclic anhydride monomer set M2 was condensed to yield the library Li (step g), made by 90 individuals organized in 10 pools of 9 encoded individuals each. 

To make this preparation useful, the equilibrium is driven to the right by removal of the acetic acid by careful distillation. This is often the method of choice for the preparation of cyclic anhydrides, in which the equilibrium is favored by entropy ... 

Cyclic anhydrides can be used to make keto-acids. Either carbonyl group is used for the acylation and the other becomes an AICI3 complex until work-up. Thus 3-benzoylpropanoic acid can be prepared from benzene and succinic anhydride. 

Naphthalene, anthracene and phenantlirene can be prepared by an intramolecular Friedel-Crafts reaction in which initially a cyclic anhydride reacts with benzene or naphthalene. 

Carboalkoxy acyl halides are made from mono esters of dibasic acids and thionyl chloride or phosphorus pentachloride. Examples are numerous. Halides with the ester group in the beta position are unstable to prolonged heating. Alkyl halide is eliminated with the formation of an anhydride. Under certain conditions a rearrangement occurs in the preparation of ester acid chlorides. The product obtained is a mixture of the expected compound and its isomer in which the ester and acid chloride groups are interchanged, viz., ROjCCHR (CI ) CO,H — RO,C(CH,) CHR COQ. The cyclic anhydride is a likely intermediate. ... 

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