Visible-light-promoted oxidative desulphurisation: a strategy for the preparation of unsymmetrical ureas from isothiocyanates and amines using molecular oxygen

Abstract

A green and efficient visible-light promoted oxidative desulphurisation protocol has been proposed for the construction of unsymmetrical ureas under mild conditions with broad substrate scope and good functional group tolerance.

A Mild Photocatalytic Synthesis of Guanidine from Thiourea under Visible Light

“…In recent years, photochemical reactions mediated by visible light have drawn significant attention in the organic synthesis community. − The process allows utilization of low energy and highly abundant visible light in the solar spectrum to perform chemical reactions via the utilization of photocatalyst creating a new paradigm of environmentally friendly processes in organic transformation. Among them, photocatalytic oxidation of various organosulfur compounds under visible light has been established − and, more recently, visible-light-induced desulfurization of organosulfur followed by amination has been applied in C–N bond construction. Tan and co-workers demonstrated a visible-light-promoted amide formation from the reaction between amines and potassium salts of thioacids .…”

The Selection of the Best Derivatization Reagents for the Determination of Polyamines in Home-Made Wine Samples

“…All polyamines reacted with BPI to form urea groups with a C=O moiety, with chemical shifts in the range of 154.43–155.87 ppm ( Figure 3 ). The desulfurization reactions of thioureas to ureas are known, but usually require the participation of oxidants; although, reactions with oxygen are also known [ 34 ].…”

Visible‐Light‐Initiated Cascade Reaction of 2‐Isothiocyanatonaphthalenes and Amines under Additive‐ and External Photocatalyst‐Free and Mild Conditions

“…These results suggested that the present photocatalytic reaction proceeds through a free‐radical pathway. The treatment of 9,10‐dimethylanthracene ( 5 a ) under the optimal reaction conditions delivered the endoperoxide product ( 5 b ) via [4+2] cycloaddition reaction, in which singlet oxygen ( 1 O 2 ) was probably involved (Scheme 3b) [7] . The experimental results of ultraviolet‐visible absorption‐spectra showed that the products 3 could absorb visible light at 385–390 nm and might serve as a photocatalyst (Figure 3), thus avoiding the employment of an external photocatalyst.…”