Suzuki cross-couplings of (hetero)aryl chlorides in the solid-state

Abstract

The ultrasound-assisted cross-linking of chitosan with hexamethylene diisocyanate with the simultaneous incorporation of Pd(OAc)2 resulted in a catalyst which is suitable for the solid-state Suzuki cross-coupling of poorly reactive (hetero)aryl chlorides with phenylboronic acid. Reactions were carried out solvent-free in planetary ball mill allowing the catalyst to be recycled several times.

Solvent-free 1,3-dipolar cycloaddition of azomethine imines with terminal alkynes promoted by calcium fluoride under the ball milling condition

“…Mechanochemistry is mainly promoted by either hand grinding or ball-milling under the solvent-free condition. Indeedly, ball-milling has already been applied for the grinding of minerals into fine particles and the preparation and modification of inorganic solids [26][27][28][29] , but more recently it has rapidly developed in the areas of organic synthesis, e.g., Suzuki [30][31][32] , Sonogashira [33][34][35] , Michael [36][37][38] , aldol reaction [39][40][41][42] , Diels-Alder reaction [43,44] , and so on. Among these, only one recent report by Stolle and co-workers [45] has addressed 1,3-dipolar cycloaddition reaction of azides with alkynes by means of ball-milling, which was named "solvent-free click reaction".…”

Suzuki–Miyaura Cross‐Coupling under Solvent‐Free Conditions

“…Previous attempts to utilize aryl chlorides in the Suzuki-Miyaura reaction under solvent-free conditions led to low or no yields of coupling products, [6b,10] or required hardly accessible catalysts. [11] Aryl chlorides that do not contain non-tolerant functional groups can be coupled using PdA C H T U N G T R E N N U N G (OAc) 2 /SPhos giving > 90% yields under solvent-free conditions. Softer bases (K 2 CO 3 or K 3 PO 4 ) were used in the coupling of chlorides bearing sensitive functional groups (entries [4][5][6][8][9][10].…”

Effects of Ultrasound and Microwaves on Selective Reduction: Catalyst Preparation and Reactions

“…[ [86][87] Near an extended solid surface, the non-spherical cavity collapse drives high-speed jets of liquid into the surface, causing catalyst damage and an increase in the number of edges, crevices and kinks that expose fresh and highly active surfaces. [21] This process can produce newly exposed, highly heated surfaces.…”

“…The new metal loaded solid chitosan derivative was then successfully applied as a catalyst support for the Suzuki reaction as well as for copper-catalyzed cycloaddition reactions between azides and alkynes. [86] The polymer was then subjected to chemical reduction of the immobilized Pd(II)-species with NaBH4, resulting in a supported Pd(0) catalyst. The catalyst was characterized by FT-IR and elemental analysis of the metal content was determined by ICP-MS measurements.…”