Photochromism of several synthesised 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives

Several 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives with varying substitutions such as 9H-fluorenyl, 4-(cyclohexyl-phenyl)-2-methyl, 4-cyclohexyl phenyl, 2-phenyl-2-methyl, and 2-cyclohexyl-2-phenyl that behave as ‘intelligent material’ are reported.

Sulfanilic Acid-catalyzed Synthesis of 4-arylidene-3-substituted isoxazole-5(4H)-ones

Results:

It was found that SA act as the catalyst for the synthesis of 4-arylidene-3-substituted isoxazole-5(4H)- ones via three-component reaction of aromatic/hetero-aromatic aldehydes, hydroxylamine hydrochloride, and three β-dicarbonyl compounds (ethyl acetoacetate, ethyl 4-chloroacetoacetate, and ethyl benzoylacetate). Optimization of the catalyst quantity and solvent showed that the highest yield was achieved with 20 mol% of SA in aqueous media. 4-Arylidene-3-substituted isoxazole-5(4H)-ones have been successfully synthesized in the presence of SA catalyst.

Conclusion:

The SA catalyst could be recovered easily from the filtrate via evaporation of solvent and reused many times. The present synthetic method is a simple, green, clean, and environmentally friendliness alternative for synthesizing 4-arylidene-3-substituted isoxazole-5(4H)-ones. Reactions were performed without the use of heating, microwave and ultrasound irradiations.

Green Synthesis of 3-Substituted-4-arylmethylideneisoxazol-5(4H)-one Derivatives Catalyzed by Salicylic Acid

Background:

4-Arylmethylideneisoxazol-5(4H)-ones are a class of organic compounds with a variety of applications in the agriculture, filter dyes, photonic devices, and pharmaceutical industries. They are also used as synthetic precursors for the synthesis of other organic compounds. As a result, efforts are being made to search new and available catalyst and green methods toward their synthesis.

Objective:

The aim of this work is to investigate the catalytic activity of salicylic acid as an inexpensive, easy to handle, and safe catalyst to synthesis of some derivatives of isoxazole-5(4H)-ones in water medium.

Methods:

To aqueous solution of equal amounts of aryl/heteroaryl aldehydes, β-ketoesters, and hydroxylamine hydrochloride; salicylic acid (15 mol%) was added and the reaction mixture was stirred at room temperature for a specified periods. The precipitated product was filtered and washed with water to obtain 3-substituted-4-arylmethylideneisoxazol-5(4H)-ones. The reaction conditions were also optimized and extended to synthesis other isoxazol-5(4H)-ones.

Results:

The salicylic acid is found to possess acceptable catalytic activity for the promotion of three-component cyclocondensation of aryl/heteroaryl aldehydes, β-ketoesters, and hydroxylamine hydrochloride. The three-component reaction led to construction of 3-substituted-4-arylmethylideneisoxazol- 5(4H)-ones in good to high isolated reaction yields.

Conclusion:

The efficient and environmental friendliness procedure for the synthesis of isoxazol- 5(4H)-ones is introduced. The reaction also carried out smoothly in water as a cost-effective, simple, green, and non-toxic solvent at room temperature without using heating, microwave, and ultrasound sources.

Stereo-controlled Deamination of Ketoaziridines Using Ph3P/I2

PPh3/I2 is an efficient reagent for the stereo-controlled deamination of non-activated aziridines, N–H and N-alkyl aziridines, using. The method works gives the corresponding trans-alkenes from both cis and trans-aziridines. A plausible mechanism is proposed for the ring opening and deamination of keto-aziridines in the presence of Ph3P/I2.

Recent Advances in Three-Component Cyclocondensation of Dimedone with Aldehydes and Malononitrile for Construction of Tetrahydrobenzo[b]pyrans Using Organocatalysts

Background:

The majority of naturally occurring compounds, pharmaceuticals, and drug-candidate molecules possess heterocyclic scaffolds. In this context, tetrahydobenzo[b]pyrans are of considerable importance. In the line with the synthesis of these valuable heterocyclic compounds, the researchers tried to synthesize these molecules using different organocatalysts. The development of new strategies for three-component condensation of dimedone, various aldehydes and malononitrile for construction of tetrahydrobenzo[b]pyrans is of particular interest to organic chemists and pharmacologists.

Objective:

In this review, three-component catalyzed synthesis of tetrahydrobenzo[b]pyran compounds is introduced, focusing on the developments in the use of organocatalysts. Organocatalytic approaches were investigated for the synthesis of tetrahydrobenzo[b]pyrans. This contribution covers the literature concerning the synthesis of heterocycles referred to, in recent times.

Conclusion:

This review article is associated with the study of the three-component synthesis of tetrahydrobenzo[b]pyrans using organocatalysts. This review also provides an insight into the importance of these heterocycles. In the vast majority of these reactions, water and water-ethanol system have been used as green solvent media for implementation of them. The use of green solvents, the development of less toxic and promising reagents/catalysts as well as the design of inexpensive and reliable approaches are some of the principles of green chemistry, and most of the methods are benefited from them. Tetrahydrobenzo[b]pyrans and organocatalysts open avenue ofnew horizons. The recyclability of the many of these organocatalysts offers an additional merit for the use of these catalysts in 3-CR of aldehydes, dimedone, and malononitrile reactions.

Facial and Efficient Access to Dihydropyrano[3,2-c]Chromenes via Three-Component Reaction Using N,N-Dimethylbenzylamine As a New Organocatalyst

The N,N-dimethylbenzylamine (DMBA), as an efficient and commercially available organocatalyst was employed for the one-pot synthesis of dihydropyrano[3,2-c]chromene derivatives in ethanol medium. In this work, the one-pot Knoevenagel-Michael-Thorpe-Ziegler type cascade heterocyclization has been developed for the synthesis of dihydropyrano[3,2-c]chromene-containing heterocycles from the one-pot multicomponent condensation reaction of 4-hydroxycoumarin, malononitrile/ethyl cyanoacetate, and various aldehydes at 60°C. The salient features of this basecatalyzed reaction are mild reaction conditions, reusability of the reaction medium, shorter reaction times, and easy separation of the reaction mixture.

Adipic Acid as a Biodegradable Solid Acid Catalyst for One-Pot, Three Component Synthesis of 1-Amidoalkyl-2-naphthols

Background:

1-Amidoalkyl-2-naphthols are an attractive group of organic compounds that can be converted to oxazine heterocycles and aminoalkyl naphthols. The derivatives of 1- amidoalkyl-2-naphthols have significant biological activities and act as drug candidates.

Methods:

1-Amidoalkyl-2-naphthols were synthesized via the three-component condensation reaction of 2-naphthol, acetamide/benzamide and various aldehydes in the presence of 10 mol% of adipic acid as an organocatalyst under solvent-free conditions at 120°C.

Results:

A simple, efficient, and operative method for the synthesis of 1-amidoalkyl-2-naphtholes in the presence of adipic acid as the biodegradable catalyst is introduced. Easy operation, acceptable reaction times, eco-friendly, availability of starting materials, simple separation of products, and high yields of products are the significant results of this method.

Conclusion:

In this study, 1-amidoalkyl-2-naphthols were synthesized using commercially available reactants in excellent yields and relatively shorter times. In this process, microwave or ultrasonic waves were not used to provide energy for the reaction.