Carbon Dioxide Mediated Novel Synthesis of Quinazoline-2,4(1H,3H)-dione in Water

Benzothiazoles from Condensation of o-Aminothiophenoles with Carboxylic Acids and Their Derivatives: A Review

Nowadays, organic chemists are interested in the field of heterocyclic chemistry due to its use in the synthesis of a great variety of biologically active compounds. Heterocyclic compounds are widely found in nature and are essential for life. Among these, some natural nitrogen containing heterocyclic compounds have been used as chemotherapeutic agents. Their attachment to sugar molecules either as thioglycosides or as nucleosides analogues plays an important role in vital biological processes as well as in synthetic organic chemistry. Molecules containing benzothiazole (BT) nuclei are of this interesting class of compounds because some of them have been found to have a wide variety of biological activities. In this sense, we selected this topic to review and to then summarize the procedures related to the condensation reactions of o-aminothiophenoles (ATPs) as well as their disulfides with carboxylic acids, esters, orthoesters, acyl chlorides, amides, and nitriles. The condensation reactions with carbon dioxide (CO₂) are included. Conventional methods with the use of acid and metal catalysts as well as recent green techniques, such as microwave irradiation, the use of ionic liquids, and ultrasound (US) chemistry, which have proven to have many advantages, were found in the review.

ZnCl2-promoted domino reaction of 2-hydroxybenzonitriles with ketones for synthesis of 1,3-benzoxazin-4-ones

A ZnCl2-promoted synthesis of 1,3-benzoxazin-4-one from 2-hydroxybenzonitriles and ketones was developed. This method displays facile access to a diverse range of substituted 1,3-benzoxazin-4-ones in good yields. This synthetic protocol has advantages: (i) easy availability of starting material; (ii) strong corrosive acid-free condition; (iii) high yield.

CO2 involved synthesis of quinazoline-2,4(1H,3H)-diones in water using melamine as a thermoregulated catalyst

In this study, pharmaceutically relevant quinazoline-2,4(1H,3H)-diones were synthesized eco-efficiently by cycloaddition of CO2 and 2-aminobenzonitrile in water, catalyzed by melamine as a thermoregulated catalyst. Quinazoline-2,4(1H,3H)-dione was produced selectively with 92% yield at 120 °C, 4.2 MPa, and automatically separated from the hot catalytic aqueous solution, which was reused directly for several runs until its activity decreased in an obvious manner. Then, the catalyst melamine was recrystallized from the spent aqueous solution via simple cooling and reused for another several catalytic runs. The efficient valorization of CO2 and the straightforward stepwise recovery of the products and catalyst were important to save energy and minimize process waste for the practical industrial production.

Recent Uses of N,N-Dimethylformamide and N,N-Dimethylacetamide as Reagents

N,N-Dimethylformamide and N,N-dimethylacetamide are multipurpose reagents which deliver their own H, C, N and O atoms for the synthesis of a variety of compounds under a number of different experimental conditions. The review mainly highlights the corresponding literature published over the last years.