A series of new spiro[cyclopropane-1,4'-pyrazol-3-one] derivatives 3a h were synthesized by the reaction of 4-arylidene-3H-pyrazol-3-one 1 with secondary and tertiary carbanions derived from a methylene and methine group bearing both a leaving group and electron-withdrawing group, e.g. methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, tert-butyl chloroacetate, chloroacetonitrile, 2-chloro-N,N-diethylacetamide, methyl 2-chloropropionate and 2-chloropropionitrile, in the presence of sodium hydride. All the synthesized compounds 3a h were active against Candida albicans with MIC 25 μg/mL in vitro.

As a part of systematic investigation of synthesis and biologically active compounds of thiazolidine (TZD) derivatives containing pyrazole ring system, several new pyrazole-TZD derivatives 8aÀd and 9aÀd have been synthesized. Compounds 8aÀd were prepared from N-substituted TZDs 6aÀd and 1H-pyrazole-4carboxaldehyde 7 by Knoevenagel-type reaction. Treatment of 8aÀd with sodium hydride at room temperature caused dimerization reaction to afford the corresponding spirocompounds 9aÀd. All the synthesized compounds were characterized by spectroscopic analysis. In vitro, the synthesized compounds 8aÀd and 9aÀd were tested for their growth inhibitory activity in A549 lung cancer, B16F10 murine melanoma, and HeLa human uterine carcinoma cells and for their differentiation of 3T3-L1 preadipocytes to adipocytes. The results showed that compound 8c possessed growth inhibitory effect of B16F10 cells (IC 50 ¼ 27 lM) and compounds 9c,d had induction effect on the differentiation of 3T3-L1 preadipocytes.

The unusual formation of 1‐acyl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones starting from 3‐acyloxypyrazoles by Fries‐type rearrangement is described. Under normal conditions, acylation of 2,4‐dihydro‐3H‐pyrazol‐3‐ones 1 and 2 with acid chlorides or anhydrides in the presence of triethylamine gave the corresponding 3‐acyloxypyrazoles 3a‐f and 4a‐f. Treatment of 3a‐c and 4a‐f with Lewis acid, e.g. titanium(IV) chloride and tin(IV) chloride, caused migration of acyl groups to afford the corresponding 1‐acyl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones 5a‐c and 6a‐f. Interestingly, the reactions of 3‐acyloxypyrazoles 3e and 3f with tin(IV) chloride provided the corresponding tin(IV) complexes 8e and 8f.

An approach to pyrano [2,3-c]pyrazoles starting from spirocyclopropanepyrazoles via a ring-opening/ cyanomethylation and intramolecular cyclization is described. Reactions of spirocyclopropanepyrazoles 1a-d with chloroacetonitrile in the presence of sodium hydride gave the corresponding cyanomethoxypyrazoles 4a-d. Treatment of 4a-d with sodium hydride at room temperature caused intramolecular Michael addition reaction to afford the corresponding pyrano[2,3-c]pyrazoles 5a-d.

The one-pot synthesis of 4-alkoxy-5,6-dihydro-furo(and -thieno) [2,3-d]pyrimidines is described. The reactions of 2-benzamido-4,5-dihydro-3-furan(and -3-thiophene)carbonitriles 1a-d and 2a-c with ethanol and/or methanol in the presence of zinc chloride and triethylamine gave the corresponding 4-alkoxy-5,6-dihydro-furo(and -thieno) [2,3-d] pyrimidines 3a-d, 4a-d, 5a-c and 6a-c.