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This research article focuses on the pathway for metal‐free unprecedented one‐pot three‐component synthesis of biologically active 3‐pyrazolyl‐thiazolidin‐4‐one derivatives through cyclo‐condensation of aromatic aldehydes, 1H‐pyrazol‐3‐amine and thioglycolic acid in aqueous medium. p‐Toluene sulphonic acid (PTSA), a non‐toxic, cheaper, easily accessible, eco‐benign, organic acid‐catalyst was explored to mediate this reaction. Formation of novel 3‐pyrazolyl‐thiazolidin‐4‐one derivatives, environment‐benign conditions, quick reaction time, excellent functional group acceptance and moderate to high yield of the products are some of the chief advantages of the reaction. Further, this methodology will surely contribute in various fields of synthetic organic methodology, pharmaceutical industry and natural bio‐active product synthesis. [ABSTRACT FROM AUTHOR]

A novel concept for the direct reductive amination of aldehyde and ketones has been developed which uses largely available, low cost and harmless L‐ascorbic acid as sustainable, versatile, non‐toxic catalyst and NaBH4 as a reductant. Described herein is a one‐pot conversion of effortlessly accessible primary and secondary amines to biologically active secondary and tertiary amines respectively in water at room temperature within 15–45 minutes. The generality of reaction was established by using various aromatic and aliphatic aldehydes, ketones and amines with 20 examples ranging from 65 to 97 % yield. The mild condition, environmentally benign byproducts and broad scope of makes this transformation very useful. [ABSTRACT FROM AUTHOR]

β‐Cyclodextrin, a robust organocatalyst has been explored for the straightforward and facile synthesis of tetrazolo[1,2‐a]pyrimidine and [1,2,4]triazolo[1,5‐a]pyrimidine derivatives through one‐pot three‐component tandem annulations reaction under solvent‐free condition using aldehyde, active methylene compound and 5‐aminotetrazole or 3‐amino‐1,2,4‐triazole respectively. This greener chemical procedure has advantages such as shorter reaction time, absence of toxic and hazardous catalyst, chemicals and solvent, highly functional group tolerance, easy work up procedure and product separation. [ABSTRACT FROM AUTHOR]

Several efficient, robust, versatile and straightforward strategies for the diversity-oriented convergent synthesis of a vast range of highly functionalized biologically active N-heterocycles such as quinoxaline, pyrazine, cyanopyrazine derivatives from different easily accessible, inexpensive starting motif has been reported by exploring the promising organo Cu (II) catalyst via double condensation/tandem oxidation-cyclization/elimination-cyclization reactions. These methodologies have several advantages such as inexpensive, non-toxic starting materials as well as catalyst and easy reaction set-up. Avoid the use of hazardous materials has added another important advantage in these protocols. [ABSTRACT FROM AUTHOR]

An environmentally benign, robust and straightforward protocol has been developed for the synthesis of a diverse array of 2,3‐dihydroquinazolin‐4(1H)‐ones using 2‐aminobenzamide and various aldehydes or ketones. Water, a green solvent was adopted in this methodology replacing hazardous reaction mediums. Further, ascorbic acid, an organocatalyst has been accepted to meet the role of catalyst, thus bypassing the use of noxious metals or hazardous materials, which is another asset of this protocol. The activity of this novel methodology has been further being broadened using an oxidant oxone to synthesize 2‐substituted quinazolin‐4(3H)‐one from aldehyde. [ABSTRACT FROM AUTHOR]

Glycerol, a green, bio‐degradable, benign solvent has been recognized to act as a highly efficient medium for the catalyst free synthesis of a vast range of highly functionalized thioamide by modified Willgerodt‐Kindler Reaction and 4H‐thiopyran via one‐pot multi‐component synthesis from easily accessible precursors. These protocols avoid hardnosed reaction conditions and proceed without any metal catalyst or toxic acid or solvent. In addition, these protocols have numerous advantages such as shorter reaction time, high yield and excellent functional group tolerance. Further the solvent can be recovered and reused at the end of the reaction which makes this methodology inexpensive, greener and environmentally safe protocol. [ABSTRACT FROM AUTHOR]

β-Cyclodextrin, a green and widespread supramolecular catalyst, has been explored as a highly proficient promoter for the metal-free one-pot multi-component synthesis of a vast range of highly functionalized bioactive heterocyclic moiety, 2-amino-4,6-diphenylnicotinonitriles and 2,3-dihydroquinazolin-4(1 H )-one, from easily available precursor aldehydes. The main endeavor of these protocols is to explore this organic supramolecule in one-pot multi-component synthesis. Absence of metal catalyst or toxic acid and harsh reaction conditions, excellent functional group tolerance, inexpensive, greener and environmentally safe protocol are the key advantages of this work., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)