286. Synthesis of heterocyclic compounds from δ-unsaturated 1,3-diketo-esters. Part II. α-Substituted styrylpyrazole- and styrylisoxazole-carboxylic esters

Exploring Three Avenues: Chemo- and Regioselective Transformations of 1,2,4-Triketone Analogs into Pyrazoles and Pyridazinones

“…Yield 0.597 g (77%); yellow powder; mp 105 °C (litr. 112 °C [ 87 ]); 1 H NMR (400 MHz, CDCl 3 ) δ 1.42 (t, J = 7.1 Hz, 3H, OCH 2 C H 3 ), 2.53 (s, 3H, CH 3 ), 4.45 (q, J = 7.1 Hz, 2H, OC H 2 CH 3 ), 7.37–7.40 (m, 2H, 2CH Ar ), 7.45–7.46 (m, 3H, 3CH Ar ), 7.50 (s, 1H, CH); 13 C NMR (125 MHz, CDCl 3 ) δ 14.3 (CH 3 ester ), 28.7 (Me), 61.5 (CH 2 ester ), 114.8 (CH), 126.0 (C Ph ), 128.7 (C Ph ), 129.3 (C Ph ), 140.0 (C Ph ), 140.8 (C pyr ), 143.7 (C pyr ), 161.5 (C=O ester ), 187.1 (C=O); Anal. calcd.…”

Synthetic Routes to Pyrazole‐3(5)‐carboxylates

“…δ,ϵ‐Unsaturated 2,4‐diketoesters 10 were prepared by condensation of ethyl oxalate with methyl styryl ketones 9 . Compound 10 reacted readily with phenylhydrazine, giving ethyl l ‐phenyl‐5‐styrylpyrazole‐3‐carboxylates 11 (Scheme ) .…”

An Efficient Synthesis of Isomeric 1‐(1‐Alkyl‐1H‐pyrazolyl) Ethanones

“…Acylpyrazoles are the important intermediates in the synthesis of pyrazole derivatives. The described methods of their synthesis are: interaction of organomethallic (Li or Mg) derivatives of pyrazole with nitriles , acyl chlorides , or anhydrides of carbonic acids , decarboxylation of pyrazol ketoacids , by oxidation of alcohols or propenyl substituted pyrazoles , by condensation of polycarbonyl compounds with hydrazines , by multistep synthesis started from substituted alkynes , by catalytic carbonilation of pyrazoles in the presence of Ru 3 (CO) 12 and by other methods. 4‐Acylpyrazoles were also obtained by direct acylation of pyrazoles by acyl chlorides under drastic conditions (150–200°C).…”