Aim and Objective: In the chemical literature, there is very little data about copper catalysed synthesis
of diaryl sulfides in water. In this work we present a novel highly selective Cu-catalysed “on-water” method
of the synthesis of symmetrical and unsymmetrical sulfides from aryl iodides and 2-mercaptobenzoxazole as a
novel sulfur transfer agent.
Material and Method: 2-Mercaptobenzoxazole was presented as a novel sulfur transfer agent. Novel Cucatalysed
“on-water” method for the selective synthesis of diaryl sulfides from diaryl iodides in the phase
transfer catalytic system 2-mercaptobenzoxazole / CuI / proline/ KOH/ Adogen 464 was developed.
Results: We have elaborated the novel catalytic system 2-mercaptobenzoxazole / KOH / CuI / Adogen464 /
proline for the synthesis of diaryl sulfides from corresponding aryl iodides in water. The products were isolated
in 30-76% yields. Modification of the presented method was successfully applied in the preparation of unsymmetrical
sulfides. For example, benzylphenylsulfide and benzyl(3-fluorophenyl)sulfide were selectively prepared
in 68% and 57% yields, correspondingly, by three-component, one-pot coupling reaction in the system
PhCH2Br (1 mmol) / ArI (1 mmol) / 2-meracaptobenzoxazole (1 mmol) / CuI (20 mol.%) / proline (20 mol.%)/
Adogen464 / H2O at 160°C.
Conclusion: Thus, novel Cu-catalyzed “on-water” method for the synthesis of symmetrical and unsymmetrical
sulfides in the system aryl iodides (and benzyl bromide) /2-mercaptobenzoxazole / KOH / CuI / Adogen464 /
proline / H2O was presented. Interestingly, similar reaction of 2-mercaptobenzothiazole in the above system led
only to 2-arylsulfanylbenzothiazoles. According to our point of view, the presented method is the best for the
selective preparation of sulfides possessing NH2, Br and F functional groups.