Pressure as effective green technology for synthesis of polyfunctionally substituted heteroaromatics: Synthesis of a variety of pyrazolo[1,5-a]pyrimidines

Abstract

Pyrazole molecules are in the forefront of organic chemistry due to their various encompass substituents, which have many biological activity sequence. The biological and medicinal activities of pyrazolo[1,5-a]pyrimidines have received considerable interest in this regard. We reported here a comparison between reaction of 4-phenylazo-3,5-diaminopyrazole (4) with ethyl propiolate (15), dimethylacetylene dicarboxylate (20), diethyl fumarate (25) and benzylidenemalononitrile (11) in the presence of catalytic amount of piperidine. We initially followed literature procedure (method A), then utilizing ultrasound irradiation (method B), microwave heating (method C) and in a Q-tube (method D). We confirmed the structure of the product by analytical spectroscopic methods. Method (D) gave a good yield with a record reaction time. KEYWORDS Q-tube High yields Record time Green technology Pyrazolo[1,5-a]pyrimidines Reactions under increased pressure

The Q-tube System, A Nonconventional Technology for Green Chemistry Practitioners

“…An interesting comparison between conventional heating and nonconventional conditions was very recently performed by AlMarzouq et al [20]. The reaction between a diazene and some electron poor double and triple bonds in absolute ethanol gave the target structures 11-14 depicted in Scheme 6, this was used as model to compare the four different methodologies ( Table 3).…”

The development of an unexpected Cu(I)‐pyrazolo pyrimidine‐based complex: Synthesis, spectroscopic characterizations, and biological activity

“…These purine analogs have a wide range of biological applications including anticancer, anti‐inflammatory, antioxidant, antimicrobial, antidiabetic, and anti‐Alzheimer's activities. [ 1–5 ]…”

“…These purine analogs have a wide range of biological applications including anticancer, anti-inflammatory, antioxidant, antimicrobial, antidiabetic, and anti-Alzheimer's activities. [1][2][3][4][5] On the other hand, pyrazoles were used to generate fused pyrazole compounds such as heterocyclic azo pyrazole dispersion dyes, which have great importance in the pharmaceutical and drug industries. [6] Azo dyes have versatile industrial applications, such as dyeing textile, food, cosmetic production, solar cells, and biomedical studies.…”

Reactions under increased pressure: The reactivity of functionally substituted 3-oxo-2-arylhydrazones toward active methylene reagents in Q-tube

“…It also increases the rate of reaction conditions and enhances the formation of transition state with negative activation volume [9]. As a result of this, we turned to utilize reactions in Q-tube (a safety device that enables conducting reactions in the laboratory), and successfully we could produce several articles whose results are outlined in Scheme 3 and 4 [10][11][12]. Our aim is to develop a novel and efficient protocol for the synthesis of cyclic derivatives with multi-component reaction (MCR) which includes a condensation reaction utilizing a Q-tube safe reactor in a short time with high yield.…”