Orthoformic acid amides esters

Sulfuric acid orthoformic acid ester Subst. carboxylic acid amides from iminoesters... 

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. ... 

The cyclic anhydride was converted into the amide acid which on Hofmann rearrangement followed by lithium borohydride reduction on the ester gave a derivative of ip-amino-2a, 3a-dihydroxy-43-hydroxy-methylcyclopentane. Condensation of the amino-triol with 5-amino-4,6-dichloropyrimidine followed by ring closure with triethyl orthoformate gave the 6-chloropurine derivative which on treatment with ammonia gave 11. ... 

Uracil and thymine derivatives are obtained from cyanoacetic acid and A -alkylurethanes. An amide 16 is formed first, which condenses with orthoformic ester to give the enol ether 17 aminolysis of 17 leads to 18 which on cyclization yields 5-cyanouracil 19 Shaw synthesis) ... 

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],... 

The reactions of the anhydride 2 and the hydrochlorides of a-amino-p-indolyl- or a-amino-p-(5-methoxyindolyl)propionic acid 170 give high yields (97 and 88%) of the corresponding amides 171. When heated with orthoformic ester in the presence of TsOH the latter undergo cyclization to the condensed pentacyclic compounds 172 (yields 66 and 69% respectively) [101],... 

Aldehydes react with the lithio-derivatives of a-diazo-esters to give /3-hydr-oxy>a-diazo-esters, which in turn undergo rhodium(ii)-catalysed decomposition to give /3-keto-esters./3-Keto-amides are obtained in moderate to high yield from the acylation of amide enolates with mixed anhydrides. In a general reaction, orthoformates react with acidic methines to give /3-keto-aldehydes, isolated as their dialkyl acetals [equation (16)]. ... 

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