Simple and Highly Efficient Synthesis of Thioamide Derivatives Using β‐Cyclodextrin as Supramolecular Catalyst in Water

Abstract

A simple, straightforward and highly efficient approach for the synthesis of thioamide derivatives in water at 100 oC has been developed. Total 22 compounds were prepared via a one‐pot multicomponent reaction between substituted aldehydes, sulfur powder and secondary amines by using recyclable catalyst β‐cyclodextrin indicating the broad substrate scope of this method. The salient features of the present protocol are water as a green solvent, non‐toxic catalyst, good to excellent yields of products, operational simplicity, eco‐friendliness and easy isolation of products. The used catalyst was recovered and reused several times without significant loss of catalytic activity, which is an essential parameter of green synthesis.

One‐pot Three‐component Solvent‐free Tandem Annulations for Synthesis of Tetrazolo[1,2‐a]pyrimidine and [1,2,4]triazolo[1,5‐a]pyrimidine

“…To screen for the optimal catalyst for the sovent-free synthesis of tetrazolo[1,2-a]pyrimidine and [1,2,4]triazolo[1,5a]pyrimidine, the previous reaction was performed using graphene oxide, ascorbic acid, boric acid, humic acid, copper acetate, glycerol, FeCl 3 ⋅ 6H 2 O and β-cyclodextrin as catalysts Reaction of benzaldehyde (1 mmol), 5-aminotetrazole (1 mmol), ethylacetoacetate (1 mmol) and catalyst (10 mg) at 90 °C under solvent-free condition for 1 h; [b] Isolated yield after column chromatography.…”

“…Hydrophobic cavities of cyclodextrins facilitate them to bind with substrates selectively which makes them a good catalytic agent in chemical reactions ensuring high selectivity. [1] CDs are able to reversible host-guest complex with the substrates via non-covalent bonding thus create a complex which is conscientious for the alteration of product distribution during the course of organic reactions. This feature shown is owing to arises of geometrical obliges developed in the guest molecules as it gets incorporated inside the cavity of CDs.…”

“…Further, since large quantity of nitrogen are there in the ring of tetrazole and triazole fused with pyrimidines are also known to demonstrate a diverse array of biological and pharmacological properties (Figure 1) such as anticancer, [3] antiplatelet and vasodilator, [4] antidiabetic, [5] antitumor, [6] antihypertonic, [7] antidepressant, [8] antituberculosis, [9] inhibitor of Hepatitis B Virus Surface Antigen Secretion, [10] antihypertensive, [11] antineoplastic activity, [12] anticonvulsant, [13] antibacterial, [14] antiviral, [15] T cell activation, [16] TIE-2 and/or VEGFR2 inhibitory activities, [17] lymphocyte specific kinase [18] protein kinase inhibitor, [19] and DNA topoisomerase I. [20] So, synthesis of these most generous and essential Nheterocyclic compounds, tetrazolo[1,2-a]pyrimidine and [1,2,4]triazolo [1,5-a] pyrimidine is considered to be one of the most attractive areas in organic chemistry. Most proficient and simplistic way to produce tetrazolopyrimidine and triazolopyrimidine are one-pot three-component reactions of 5-aminotetrazole or 3-amino-1,2,4-triazole, active methylene compounds and aldehydes respectively.…”

“…Solvent-free synthesis of eminent organic molecules is moderately recognized in the literature. [31] So, keeping these all things in mind, we are interested to explore the synthesis of tetrazolo[1,2-a]pyrimidine and [1,2,4]triazolo [1,5-a]pyrimidine through one-pot three-component protocol under solvent-free condition by a greener way using the supramolecular organocatalyst, β-cyclodextrin (Scheme 1).…”

Glycerol: A Benign Solvent‐Assisted Metal‐Free One‐Pot Multi‐Component Synthesis of 4H‐Thiopyran and Thioamides from Easily Accessible Precursors

“…Furthermore, thioamides have been synthesized by oxidative coupling of primary amine with sulphur, copper (II) catalyzed aerobic oxidation of thiols in presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene, or by reaction of formamide with aldehyde and sodium sulphide in presence of water . The usefulness and activity of sulphur as a reactant has also been previously exploited in some organic methodologies in literature– and also in the Willgerodt‐Kindler reaction which is another alternative route to the synthesis of thioamide from aldehydes and amines using sulphur –. But due to the harsh reaction conditions, longer reaction time and use of expensive catalyst, these protocols did not gain much attention for a long period of time.…”