Anhydride compounds

Carboxylic acid anhydrides compounds of the type RCOCR can also serve as sources of acyl cations and m the presence of aluminum chloride acylate benzene One acyl unit of an acid anhydride becomes attached to the benzene ring and the other becomes part of a carboxylic acid... 

Figure 1.69 SAMSA is an anhydride compound containing a protected thiol. Reaction with protein amine groups yields amide bond linkages. Deprotection of the acetylated thiol produces free sulfhydryl groups for conjugation.

Acylation reactions to block amine groups on PAMAM dendrimers with anhydride compounds are done in a similar manner to glycidol modification. The following protocol is based on the method of Majoros et al., 2005. 

Many other functional silane coupling agents are available from commercial suppliers, including hydroxyl, aldehyde, acrylate and methacrylate, and anhydride compounds. Substrate modification procedures similar to those discussed above can be used with these reagents to link a biomolecule to an inorganic surface or particle. 

PEG contains no carboxylate groups in its native state, but can be modified to possess them by reaction with anhydride compounds. Either PEG or mPEG may be acylated with anhydrides... 

Most compounds of this type are cyclic sulfite and sulfate esters of aromatic 1,2-diols as well as anhydrides of aromatic 1,2-disulfonic acids. The simplest representatives with unsubstituted benzene rings are 1,3,2-benzodioxathiole 2-oxide (48) (catechol sulfite), the corresponding 2,2-dioxide (156) (catechol sulfate) and 2,1,3-benzoxadithiole 1,1,3,3-tetroxide (158) (1,2-benzenedisulfonic anhydride). Compound (48) was synthesized by refluxing catechol with thionyl chloride in the presence of pyridine. In a similar fashion, from 2-mercaptophenol 1,2,3-benzoxadithiole 2-oxide was prepared (81AG603). The dioxide (156) was obtained in two steps by reaction of catechol monosodium salt with sulfuryl chloride in benzene at 0-10 °C and subsequent reflux of the intermediate (155) in the presence of pyridine. 

Alkenes were reacted with thallium triacetate and azidotrimethylsilane to give 0-azidoalkyl thallium compounds, which were converted in situ to aziridinylazothallium compounds70,71. Only in the case of norbornene derivatives were the initial adducts (cxo.cw-azido-thallium compounds) isolated72. The aziridinylazothallium compound derived from cyclohexene 1 underwent thermal decomposition to give the trans-1,2-diazide, 2 in low yield. However, on treatment with acyl halides or trifluoroacetic anhydride, compound 1 afforded the corresponding 0-halo or 0-trifluoroacetoxy azides70. 

Imide.—When ammonium acid succinate is heated water is lost in two steps. First, succinamic acid is obtained and then an anhydride compound. The same compound is also obtained when the symmetrical di-amide is heated and a molecule of ammonia is lost. The compound has been shown to have an inner anhydride structure exactly analogous to succinic anhydride and is known as succin-imide. The reactions may be represented as follow ... 

Acid anhydride Compound of the general type R C COR2. May be symmetrical or mixed. 

BERNSTEIN, D.I., GALLAGHER, J.S., D SOUZA, L. BERNSTEIN, I.L. (1984) Heterogeneity of specific-IgE responses in workers sensitized to acid anhydride compounds. Journal of Allergy and Clinical Immunology, 74, 794—801. 

Isomeric [l,5-u]-analogues of 291 can also be obtained by treatment of 1,2-diamino-7,8-disubstituted purine-6,8-diones 290 with carboxylic anhydrides. Compounds of this type are potential B-cell-selective activators and the 6-methyl-l-(2-piperidinoethyl)-3-/l-D-ribofuranosyl-derivate of 291 was shown to be an example (94JMC3561) (Scheme 83). 

Ytterbium(lll) tris(perfluoroalkanesulfonyl)methides 34 are effective catalysts (10% mol) for the Friedel-Crafts acylation of arenes with anhydrides. Compounds 34 can be prepared as described in Scheme 3.7. Trimethylsilylmethyl lithium 31 is reacted with commercially available per-fluoroalkanesulfonyl fluorides, giving intermediates 32 that can similarly produce tris-perfluoroalkanesulfonyl derivatives 33. These compounds are converted into the catalysts 34 by reaction with ytterbium oxide. It is shown that the highly fluorinated catalyst (34, Ri = C5F13, = C8F17) (10% mol)... 

The Friedel-Crafts reaction is also effective on anhydrides and goes once only with cyclic anhydrides. Compound (26) was used in the synthesis of fungicidal compounds, ... 

Alternarively, the azeohopic condensation technique is used to remove the water. In the modified direct polymerization route, diaminodi-phenyl ether, m-phenylenediamine (MPD) and trimellitic acid anhydride in a ratio of total 1 mol of diamino compound and 2 mol of anhydride compound are condensed in NMP using xylene to remove the water formed. The resulting diimidedicarboxylic acid is treated with thionyl chloride to form the acid chloride on the fly and the PAl is created by adding a mixture of diaminodiphenyl ether and MPD. ... 

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