Orthoformic acid amides

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

Without additional reagents Formamidinium salts from orthoformic acid amides... 

The acid amide (149), prepared as in Scheme 36 (Section 4.05.4.2.1), reacts with triethyl orthoformate to give the pyrazolopyridine (150) (59JA2452). Diazotization of the amine... 

In the acid-catalyzed reactions of orthoformates with primary carbon acid amides or urethanes tris(acylamino)methanes (537 Scheme 98) are formed with good yields. - Dimethylamino-di(phthalimido)methane (531) is accessible from phthalimide and DMF diethyldithioacetal. Lithium di-methylamide, prepared in situ from lithium and dimethylamine in HMPA converts orthoformates to tris(dimethylamino)methane (529). ... 

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

There is also the possibility of removing the 2-oxo group by ring cleavage and subsequent recyclization. Lumazine can be hydrolyzed by strong alkali to 2-aminopyrazine-3-carboxylic acid (153) which is converted first into the amide (154) and then cyclized by ethyl orthoformate into pteridine-4-one (155 equation 47) (51JCS474). 

Acetals have been used in the presence of Lewis acids, particularly zinc chloride and ferric chloride, for the addition of phosphorus-halogen species to prepare 1-alkoxyphosphonic dichlorides and dialkyl 1-alkoxyphosphonates (from phosphorus trichloride and dialkyl phosphinous chlorides, respectively).143-145 It should be noted that good yields of these types of products have also been reported in the absence of catalysts.146 147 Other types of substrates have also been used in these types of processes. These include acylals,148 amidals,149 orthoformates,150 and orthoacetates.151... 

The unsubstituted 1,2,4-oxadiazole has been prepared from formamidoxime and the mixed anhydride of acetic and formic acid, or formamide <67BSB92>. 5-Unsubstituted 1,2,4-oxadiazoles are formed by heating the condensation products of amide oximes with formic acid <63CI(M)1238>. Alternatively, amidoximes are treated with triethyl orthoformate in the presence or absence of... 

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