Orthoformic acid derivatives

Alkyl aryl ketones can be converted to arylacetic acid derivatives in an entirely different manner. The reaction consists of treatment of the substrate with silver nitrate and I2 or Br2, ° or with thallium nitrate, MeOH, and trimethyl orthoformate adsorbed on Montmorillonite K-10 clay, an acidic clay. ... 

A patent procedure for formation of compounds 19 from simple tartaric acid derivatives has appeared <06USP047129> and various new routes to chiral dioxolanones include synthesis of dioxolan-2-ones either by transition metal-mediated asymmetric synthesis <06T1864> or enzyme-mediated kinetic resolution <06H(68)1329> and a new synthesis of the chiral dioxolan-4-ones 21 from lactic or mandelic acid involving initial formation of intermediates 20 with trimethyl orthoformate in cyclohexane followed by reaction with pivalaldehyde <06S3915>. 

Quinolylaminomethylenemalonates (267) were prepared in the reactions of 2-aminoquinoline, ethyl orthoformate, and malonic acid derivatives (266) in the presence of A1C13 at 135-140°C for 30 min (74MIP1). 

For example, 4-(ethoxymethylene)-2-(l-naphthyl)-5(4//)-oxazolone 812, an intermediate for fluorescent 4-(A -substituted-aminomethylene)-2-(l-naphthyl)-5(4//)-oxazolones 813, was prepared from 1-naphthoylglycine and triethyl orthoformate.Reaction of 812 with amino acids gave the corresponding amino acid derivative 813 as a mixture of stereoisomers as shown in Scheme 7.249. 

Recent examples of the methods described in CHEC(1984) and CHEC-II(1996), and involving condensation of a substituted pyrimidine with a Ci unit, include the condensation of 3-amino-4-cyanopyrimidines with orthoformates <1995W095/19774> and a variety of carboxylic acid derivatives <1995EJM525, 1996JIC698, 1998JRM2880, 2002EJC995>. 

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). 

These have the general formula R1,C(OR2)3 and are stable derivatives of the unstable ortho acids R-C(OH)3. Important examples are the esters of orthoformic acid (the orthoformates), which may be readily prepared by the interaction of the appropriate sodium alkoxide with chloroform (Expt 5.153). 

For a complete study of symmetric orthoformic acid, we have to deduce the full NRG. The full Hamiltonian operator for the internal and external rotations, may be derived if we consider ... 

In order to achieve this comparison between the Longuet-Higgins and Altmann s theories, and the present NRG one, let us consider again the orthoformic acid molecule, but in a random configuration such cis upper one shown in Fig. 10. From this configuration, it is easily seen that six different isoenergetic structures may be derived from one of them, for example, by permutations and permutations-inversions of the identical nuclei ... 

A 2- or 6-hydroxy-substituted purine can be prepared from the corresponding 4,5-diamino-pyrimidinol by cyclization with an acid, ester, ortho ester, or amide. If the ring closure is performed with reagents such as urea, alkyl chloroformates, urethanes, phosgene, and alkyl isocyanates, the 8-hydroxypurines are formed. Various xanthine and uric acid derivatives have been prepared by the condensation of 5,6-diaminopyrimidine-2,4-diols with formic acid. Purin-2-ol (1) was prepared by this route from 4,5-diaminopyrimidin-2-ol and ethyl orthoformate. ... 

Intramolecular Friedel-Crafts reaction Worthy of mention is the case of intramolecular Friedel-Crafts-type reaction affording 4(lH)-quinolone derivatives [443]. Thus, after extensive investigations, the authors prepared a solid-supported Meldrum s acid derivative by alkylation of a Merrifield resin with ethyl acetoacetate, decarboxylation, and subsequent ketalization of the resulting supported ketone with malonic acid (638). Treatment with triethyl orthoformate and various arylamines (639) afforded immobilized arylamino-methylene derivatives of Meldrum s acid (640). Upon thermal cyclization, these intermediates afforded 4(lH)-quinolone derivatives with simultaneous release from the resin (641). Highly pure final compounds were obtained in moderate to good yields. The resin was recovered in the form of the precursor of (638), i.e., the ketone (642), and thus could be potentially reused (Scheme 133). 

The formamides 16 are intermediates. Formamide (Bredereck variant of the Traube synthesis [149]), formamidine, orthoformic ester, diethoxymethyl acetate, Vilsmeier reagent (fi om DMF and POCI3) and dithioformic acid are used as formic acid derivatives. 4,5-Diaminopyrimidines can be obtained from 4-aminopyrimidines 17 by nitrosation with HNO2 followed by reduction of the nitroso compounds 18 ... 

As stated above, the synthesis of quinazoline derivatives can also be conducted in two stages, i.e., by the reaction of isatoic anhydrides with ammonia, amides, and various compounds containing the NH2 group followed by cyclization of the obtained anthranilic acid derivatives. Thus, the amino amides 157, formed during the action of aqueous ammonia on the anhydrides 61 (yields 61-73%), were brought into reaction with orthoformic ester, and this led to the quinazolinones 158 (yields 53-78%) [79],... 

Triphenylacetic acid Ethylene derivatives from cyclic orthoformic acid esters... 

Without additional reagents Reaction of orthoformic acid amides with acetylene derivatives... 

Orthoformic acid esters by transesterification with cleavage of 0,0-isopropylidene derivatives... 

Upon treatment with (la), orthoformate (95) is converted into cyclic carbonate (96) by an allylic transposition [153]. This transformation is initiated by activation of the C-OMe bond of the orthoformate moiety (Scheme 9.64). The triol acid derived from (96) is a potent vasodilator. 

Orthoesters are trivially named as derivatives of ortho acids such as triethyl orthoformate [122-51 -0] HC(OC2H )2, or named systematically as ethers, 1,1,1-triethoxymethane. 

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