A Concise One‐Pot Synthesis of 3,4‐Diaryl‐1H‐pyrazoles from Natural Isoflavones and Hydrazine Hydrate

Abstract

An efficient protocol has been developed for the preparation of a series of new 3,4-diaryl-1H-pyrazoles, potential pharmacological and agricultural targets, by the reaction of hydrazine hydrate with different natural isoflavones or their derivatives. The target compounds were obtained in good-toexcellent yields (80 -95%; Table 2) under fairly mild reaction conditions (808) Introduction. (¼ 5,7-dihydroxy-6,4'-dimethoxyisoflavone) is an effective antidiabetic [23]. However, it is necessary to modify the structure of natural isoflavones to increase their biological activities and generally poor solubilities.Recently, we reported the synthesis of several new water-soluble isoflavones [24]. In order to enhance their biological activity and to develop more-powerful new drugs, we herein report the high-throughput synthesis of a series of new 3,4-diarylpyrazoles by means of a one-pot procedure based on the reaction of hydrazine with natural isoflavones.

A Concise Synthesis of Pyrazole Analogues of Combretastatin A1 as Potent Anti‐Tubulin Agents

“…[14] After completion of the reaction, aqueous hydrazine was added to the reaction mixture, leading to 3,4-diaryl pyrazoles 7-22. [15] As postulated, [15a] hydrazine undergoes initial 1,4-conjugate addition to the double bond of the 3-arylchromone with subsequent ring opening, followed by attack of the unsubstituted hydrazine nitrogen to the carbonyl group and cyclization. This one-pot process resulted in the formation of o-hydroxyphenylpyrazoles 7-22, providing facile construction of these heterocycles as CA1 analogues.…”

Simple and Efficient Method for Synthesis of 3-Cyano-6,7-diarylpyrazolo[1,5-a]pyrimidine from Isoflavones

“…[9,10] pyrimidine. [11] Recently, we have reported the high-throughput synthesis of 3,4-diarylpyrazoles, 4,5-biphenyl-2-pyrimidinyl-guanidine, and 2,3-diarylpyrimido[1,2-a]benzimidazole by using one-step reactions of hydrazine, [12] biguanidine, [13] and 2-aminobenzimidazole [14] with isoflavones. Herein, we report a new strategy for the preparation of a wide variety of 3-cyano-6,7-diarylpyrazolo [1,5-a]pyrimidines bearing different substituents on the phenyl units from isoflavones.…”

One‐step synthesis of 2,4,5‐trisubstituted pyrimidines

“…The use of combinatorial approaches to the high‐throughput synthesis of this druglike scaffold would be a powerful advance in helping to speed up drug discovery. Recently, we have reported the high‐throughput synthesis of 3,4‐diarylpyrazoles, 4,5‐diphenyl‐2‐pyrimidinylguanidine and 2,3‐diarylpyrimido[1,2‐ a ]benzimidazole by using a one‐pot reaction of hydrazine [29], bisguanidine [30] and 2‐aminobenzimidazole [31] with isoflavones. Herein, we report a strategy for the preparation of 2‐mercapto‐4,5‐diphenylpyrimidines and 2‐amino‐4,5‐diphenylpyrimidines by the cyclocondensation of isoflavones (1) with thiourea (2a) or guanidine (2b) (Table 1).…”