Ultrasound Assisted Solvent/Metal Free Synthesis of 3‐Sulfenylindoles Employing TBATB‐Grafted MCM‐48 as a suitable Heterogeneous Catalyst.

Abstract

A one pot synthesis of 3‐sulfenylindoles in a solvent and metal free condition is reported here. The ultrasonic protocol markedly accelerates the reaction between substituted indoles and disulfides providing desired products in good to excellent yield. The ultrasonication produces local heating effect which is comparatively more advantageous than conventional heating. The method is catalyzed by TBATB impregnated MCM‐48 which is as a selective and efficient heterogeneous catalyst, also a source of molecular bromine which in presence of DMSO leads to C−S coupling. The salient feature of this protocol is easy recovery and reusability of the catalyst up to minimum five consecutive cycles. The easy and clean operation, short reaction time and high yield of desired outcomes make this method a practically applicable one.

Synergistic Effect between Ultrasound Irradiation and Na 2 CO 3 in N ‐Acylation Reaction: Applied for the Synthesis of Novel N ‐Acylcyanamide Derivatives

“…The bonding energy required for this reaction provides by the localized hot spots that produced during the cavitation collapse. Ultrasound radiation can induce cavitation bubbles, which collapse of the bubbles causes a localized increase in temperature and pressure and result in increasing the mixing intensity . Moreover, ultrasonic irradiation, with increasing the rate of the slow step and providing more energy throughout the reaction process, acts as a thermal and kinetic energy source for the reaction, which can reduce reaction time and increase product yields (76‐96%) compared to traditional methods (67‐88%).…”