D. V. Dar’in

Acetamidines and acetamidoximes containing an electron-withdrawing group at the α-carbon atom: their use in the synthesis of nitrogen heterocycles (review)*

Published information on heterocyclizations involving acetamidines and acetamidoximes substituted at the α-position with an electron-withdrawing group is reviewed, where these starting materials have been used in the synthesis of 2-aminoazaheterocycles (2-aminopyridines, 2-aminopyrroles, and 2-aminoazirines). In such reactions the α-carbon atom of the amidine or amidoxime is included in the ring of the obtained heterocycle.

Reaction of ethyl 3,3-diaminoacrylate with pyrimidine series o-chloro ketones. Synthesis of pyrido[4,3-d]pyrimidines and 6H-1,3,6,7-tetra-azaphenalenes

Cyclocondensation of ethyl 3,3-diaminoacrylate with 5-acetyl-4-chloropyrimidines gave ortho- and peri-condensed heterocycles formed through substitution of the chlorine atom by the α-carbon atom of the enediamine and condensation of the amino group with the carbonyl or by addition of the amino group to the pyridine ring.

Reactions of 3,3-diaminoacrylic acid derivatives with o-haloarenecarbonitriles. Synthesis of fused azines

The interaction of the ethyl ester or pyrrolidide of 3,3-diaminoacrylic acid with aromatic and heteroaromatic nitriles containing a labile halogen atom in the ortho position, leads to the formation of products of its substitution by the α-carbon atom of the diaminoacrylic acid derivative. The compounds obtained are cyclized smoothly into fused diaminoazines.

Synthesis of cinnoline 1-oxides by the reaction of ortho-fluoronitrobenzenes with enediamines

Reaction of α-carbonylacetamidines existing in the enediamine tautomeric form with the substituted ortho-fluoronitrobenzene afforded products of the replacement of the fluorine by the α-C atom of amidine. The latter underwent cyclization into cinnoline 1-oxides on treatment with sodium hydride.

Chemoselective cyclocondensation of α-acylacetamidines with 2-methylsulfanyl-4,6-dichloropyrimidine-5-carbaldehyde

Cyclocondensation of α-acylacetamidine with 2-methylsulfanyl-4,6-dichloropyrimidine-5-carbaldehyde proceeds chemo- and regioselectively involving replacement by the α-carbon of the amidine of the chlorine in the aromatic ring and a reaction of the amino group with the formyl group.

REARRANGEMENT OF THE ADDUCTS OF α-(AMINOCARBONYL)- ACETAMIDOXIMES WITH ACYLACETYLENES, LEADING TO 2-AMINOPYRROLE DERIVATIVES*

The rearrangement and cyclization of O-vinylamidoximes, which are adducts of α-(aminocarbonyl)-acetamidoximes with acetylenic ketones, leads to 2-acylaminopyrroles.