Microwave-assisted synthesis of the antihyperglycemic drug rosiglitazone

Study of 400 MHz microwave conduction loss effect for a hydrolysis reaction by thermostable β-Glucosidase HT1

Microwave irradiation at different frequencies gave molecular selective effects, namely higher frequency microwave effects for waters while lower frequency effects for ions. We already reported that 2.45 GHz and 5.80 GHz microwave irradiation gave different results for a hydrolysis reaction by thermostable β-Glucosidase HT1. Here, we designed and made a reactor, employed 400 MHz microwave irradiation, and studied the effectiveness of 400 MHz microwave for HT1 reaction, then 400 MHz and 2.45 GHz had the ability to accelerate HT1 reaction. In consideration of the general mechanism of enzymatic glycoside hydrolysis, our results would be reasonable if ions are key reaction species because 400 MHz microwave activated ions selectively. In addition, the phenomenon that 400 MHz microwave would not affect water molecules by dielectric heating might contribute the enzyme stability. This report should support that microwave is not only a tool to heat reactions efficiently but also can bring unique effects for reactions.

The assembly of integrated continuous flow platform for on-demand rosiglitazone and pioglitazone synthesis

Manufacturing thiazolidinediones in a batch process is often carried out at different locations, where each successive batch collects a certain amount of intermediate followed by its transportation to another location.

Reductive Aldol-type Reactions in the Synthesis of Pharmaceuticals

The efficient chemo-, regio- and stereoselective formation of saturated carbon-carbon fragment is the critical challenge of organic synthesis; therefore, developing new methods for formation of these bonds is paramount. The rising interest for reductive aldol-type reactions is conditioned by its versatile applications, allowing the efficient formation of carbon-carbon bonds. The review aims to highlight the advantages and disadvantage of reductive aldol-type reactions to total synthesis of pharmaceutical substances in order to summarize knowledge and encourage further investigation of the field.

An efficient, mild and metal free l-proline catalyzed construction of fused pyrimidines under microwave conditions in water

One-pot condensation of 4-hydroxy coumarins, aldehydes and urea/thiourea to build C-C and C-N bonds is described. Fused pyrimidines have been synthesized under mild reaction conditions using l-proline. The protocol has been performed rapidly and efficiently in water under metal free conditions. Heterocyclic derivatives have been synthesized using the present methodology and avoid the use of hazardous solvents over conventional organic solvents. A proposed mechanism could be established for three component reactions. The present study reveals the first case in which l-proline has been explored as a homogeneous catalyst in the synthesis of fused pyrimidines in water under microwave irradiation. This synthesis involves simple workup and acceptable efficiency. The most notable feature of this protocol is the ability of the catalyst to influence asymmetric induction in the reaction.

One-pot facile and mild construction of densely functionalized pyrimidines in water via consecutive C-C and C-S bonds formation

Fused pyrimidines composed of alternating heteroatoms and a pyrimidine moiety were synthesized efficiently using readily available starting material 4-hydroxycoumarin, aromatic aldehydes, and urea/thiourea at room temperature. Acid, metal salts, and surfactants were screened for their influence on catalytic activity in three-component reactions and sodium lauryl sulphate (SLS) was used as the best catalyst with different concentrations. Screening results of catalyst loading from our investigation showed that good to excellent yields were obtained with 10 mol%. Our method efficiently synthesized heterocycles and avoided the use of hazardous solvents and conventional organic solvents. Our procedure which involves a surfactant is operationally simple, environmentally benign, has excellent yields, short reaction times, and synthetically is as efficient as conventional procedures using organic solvents.

Robust Acenaphthoimidazolylidene Palladacycles: Highly Efficient Catalysts for the Amination of N-Heteroaryl Chlorides

A series of robust N-heterocyclic carbene palladacycles have been successfully developed. These showed high catalytic activity and selectivity toward the challenging amination of N-heteroaryl chlorides. Different primary and secondary amines were fully compatible with this catalytic system. Remarkably, no double amination products could be detected when primary amines were utilized in our catalytic transformation. Furthermore, the protocol has been successfully extended to synthesize rosiglitazone, a clinical drug for diabetes mellitus, highlighting its potential pharmaceutical feasibility.

Copper-catalyzed O-arylation of N-protected 1,2-aminoalcohols using functionalized trivalent organobismuth reagents

The O-arylation of 1,2-aminoalcohols using functionalized triarylbismuth reagents is reported.

Efficiency of 2.45 and 5.80 GHz microwave irradiation for a hydrolysis reaction by thermostable β-Glucosidase HT1

Microwave irradiation at different frequencies gave unique results for the hydrolyses of glycosyl bonds by β-Glucosidase HT1. With the observed relative complex permittivity data for the reaction buffer, 2.45 GHz microwave radiation affected both waters and ions, while 5.80 GHz only affected waters. We, here, propose that would be one of the unique "microwave nonthermal effects".

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

This review which is the second in this series summarises the most common synthetic routes as applied to the preparation of many modern pharmaceutical compounds categorised as containing a six-membered heterocyclic ring. The reported examples are based on the top retailing drug molecules combining synthetic information from both scientific journals and the wider patent literature. It is hoped that this compilation, in combination with the previously published review on five-membered rings, will form a comprehensive foundation and reference source for individuals interested in medicinal, synthetic and preparative chemistry.

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

This review which is the second in this series summarises the most common synthetic routes as applied to the preparation of many modern pharmaceutical compounds categorised as containing a six-membered heterocyclic ring. The reported examples are based on the top retailing drug molecules combining synthetic information from both scientific journals and the wider patent literature. It is hoped that this compilation, in combination with the previously published review on five-membered rings, will form a comprehensive foundation and reference source for individuals interested in medicinal, synthetic and preparative chemistry.

Heterocycles 27. Microwave assisted synthesis and antitumour activity of novel phenothiazinyl-thiazolyl-hydrazine derivatives

A series of new phenothiazinyl-thiazolyl-hydrazine derivatives were synthesized by Hantzsch cyclization of 1-(10-ethyl-10H-phenothiazin-3-yl)-methylidene-thiosemicarbazide with α-halocarbonyl derivatives. Comparison between classical and microwave assisted synthesis emphasizes the great advantages induced by microwaves irradiation which afforded high reaction yields in much shorter reaction time. Structural assignments were based on spectroscopic methods (high resolution NMR, FTIR, MS). The new compounds were tested in vitro for their antiproliferative activity against tumor cell lines using spectrometric methods. Most of the compounds exhibit cytotoxicity against hepatic and colon tumor cells in a dose-dependent mode and a relationship between the structure and their biological activity was observed.

Progress in Microwave-Aided Chemical Synthesis

The continuing use of microwave (µwave) energy in chemical synthesis has been impressive over the past decade, with many reports incorporating µwave-based reactions. Two of the major benefits of using µwave heating are the remarkable decrease in reaction times and often high yield of products in comparison with classical heating, an ideal technology for synthetic chemists. Herein, we highlight some exciting examples of its recent utility in organic, medicinal, and natural product synthetic endeavours.