Cyclocondensation of activated ortho-chloroarylacetylenes with hydrazine: a novel route to substituted indazoles

Acetylenic derivatives of quinones

“…96 b. Cyclocondensation of 2-alkynyl-1-chloroanthraquinones Several studies were devoted to cyclocondensation of aryl-and hetarylacetylenes containing the labile chlorine atom in the ortho position with hydrazine and its derivatives. 98 ± 101 The reaction starts, apparently, with the replacement of the halogen atom 99 and always gives rise to a five-membered heterocyclic compound, viz., a derivative of pyrazole or N-substituted pyrrole.…”

A directive effect of heterofunctions in cyclocondensation reactions of acetylenylquinones with hydrazine

“…a hydroxyl group, in the acetylenic substituent; this directive effect was used for the synthesis of naphtho [2,3-h]cinnoline-4,7,12-trione and 4H-naphtho[1,8-cd]-1,2diazepin-8-one derivatives.Acetylenic derivatives of cinnoline and benzene with a labile chlorine atom at the ortho position react with hydrazine to close a pyrazole ring. [1][2][3] When continuing our studies of the heterocyclization of acetylenylquinones, 4-9 we carried out this condensation in the anthraquinone series.In 2-acetylenyl-1-chloro-9,10-anthraquinones 1, the halogen atom is readily substituted by nucleophilic groups, 10 and the triple bond activated by the quinone nucleus is efficiently attacked by N-nucleophiles. 11 This attack is directed onto the β-C atom of the triple bond.…”

“…Therefore, we supposed that the cyclocondensation of 1 with NH 2 NH 2 will result in the formation of a six-membered diazine ring rather than a five-membered diazole ring as in the above reactions. [1][2][3] In addition, competitive heterocyclization with the participation of the peri-carbonyl group can play a noticeable role.We found that anthraquinones 1 easily condense with NH 2 NH 2 (pyridine, 90-115 °C). Compounds 1a,b with no heteroatomic groups in their acetylenic substituents are transformed to only pyrazole derivatives.…”

Cross-coupling of copper arylacetylides with N-(o-iodoaryl)hydrazines as a new method of synthesising 2-substituted indoles

“…We have already reported on the cyclocondensation of activated o-chloroarylacetylenes with hydrazine which results in substituted indazoles. 1 This method is, however, limited by the necessity of using both aryl halides and acetylenic components which possess only electron-withdrawing substituents.…”

“…The same compounds are obtained by the cyclization of α-N-[(o-arylacetylenyl)phenyl]-β-N-(acetyl)hydrazine in DMF in the presense of CuI. ‡ 8a: mp 287.5-288 °C (from EtOH); 1 2. The cyclocondensation of α-N-(o-iodophenyl)-β-N-(acetyl)hydrazine with copper(I) acetylides with electron-withdrawing substituents gives 3-substituted isoindazoles under the effect of bases.…”