Cyclodesulfurization: An Enabling Protocol for Synthesis of Various Heterocycles

Abstract

Heterocycles closely intertwine chemistry with biology reflecting the presence of nitrogen‐based heterocyclic ring structure in nearly 75 % of small‐molecule drugs. The number of reported strategies for the synthesis of several “privileged scaffolds” has expanded, amongst which, cyclodesulfurization of thioureas offers a quick access to highly substituted heterocycles, thereby playing a role of an excellent tool in organic syntheses of natural products and pharmaceutically active compounds. This comprehensive review emphasizes the applications of cyclodesulfurization as an integral synthetic step in the synthesis of nitrogen, oxygen and sulfur‐containing heterocycles. Furthermore, a survey of cyclodesulfurizing agents reported since 2000 is comprehensively reviewed and summarized.

Differential transmetallation of complexes of the anti-cancer thiosemicarbazone, Dp4e4mT: effects on anti-proliferative efficacy, redox activity, oxy-myoglobin and oxy-hemoglobin oxidation

“…The species, [Ni(Dp4e4mT-S)], is suggested based on reports of transition metal-triggered partial desulfuration and intra-molecular cyclization in multiple thiosemicarbazone systems. 51–56 Interestingly, [Ni(Dp4e4mT-S)] ( m / z : 328.0) was also observed in the spectrum of [Ni(Dp4e4mT) 2 ] itself (Fig. S5B†).…”

TBHP‐Mediated Selenocyclization of N‐Allylbenzamides/Benzthioamides via In‐Situ Generation of “PhSeOH” Species**

“…An intramolecular nucleophilic attack of the oxygen or sulfur traps the seleniranium intermediate V and results in 5‐ exo cyclization product 9 (Scheme 2A). And the formation of the oxazoline counterpart in case of N ‐allylbenzthioamides as substrate could be attributed to the desulfurization property of TBHP [66,67] which results in the formation of respective N ‐allylbenzamides through intermediate VI as shown in Scheme 2B.…”

“…(Scheme 2A). And the formation of the oxazoline counterpart in case of N-allylbenzthioamides as substrate could be attributed to the desulfurization property of TBHP [66,67] which results in the formation of respective N-allylbenzamides through intermediate VI as shown in Scheme 2B.…”

Recent Progress in Heterocycle Synthesis: Cyclization Reaction with Pyridinium and Quinolinium 1,4-Zwitterions

“…Heterocycles are ubiquitous cores in natural products, bioactive molecules, functional materials, and therapeutic leads [ 1 , 2 , 3 , 4 ]. Chemists are becoming increasingly focused on developing efficient synthetic approaches for heterocyclic frameworks, where minimizing the number of synthetic steps, maximizing synthesis efficiency, and reducing side reactions are important evaluation criteria [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Among various synthetic strategies, dipolar cyclization reactions have become one of the most favored methods for the construction of functionalized heterocyclic compounds [ 16 , 17 , 18 , 19 , 20 ].…”