An environmentally benign surfactant (“TPGS-750-M”), a diester composed of racemic α-tocopherol, MPEG-750, and succinic acid, has been designed and readily prepared as an effective nanomicelle-forming species for general use in metal-catalyzed cross-coupling reactions in water. Several “name” reactions, including Heck, Suzuki-Miyaura, Sonogashira, and Negishi-like couplings have been studied using this technology, as have aminations, C-H activations, and olefin metathesis reactions. Physical data in the form of DLS and cryo-TEM measurements suggest that particle size and shape are key elements in achieving high levels of conversion and hence, good isolated yields of products. This new amphiphile will soon be commercially available.

A high reactivity of dicationic palladium(II) complexes for transmetalation of organoboron and -silicon compounds was demonstrated in the 1,4-addition of arylboronic acids or arylsiloxanes to acyclic and cyclic enones. [Pd(dppe)(PhCN)2](SbF6)2 and nitrile-free catalysts prepared in situ from Pd(acac)2, dppben, and Cu(BF4)2·6H2O or oxidation of Pd(dba)2 with Cu(BF4)2·6H2O in the presence of dppe or dppben effectively catalyzed the reactions of arylboronic acids at room temperature and arylsiloxanes at 75 °C. A catalytic cycle involving transmetalation between Ar−[m] (m = B(OH)2, Si(OMe3)) and [Pd]2+ to give an Ar−[Pd]+ intermediate, insertion of an enone into the C−Pd bond, giving a palladium enolate, and finally hydrolysis with water to regenerate [Pd]2+ species was proposed. The reaction between [Pd(dppe)(PhCN)2](BF4)2 (4a) and PhB(OH)2 in the presence of PPh3 allowed the first isolation of the transmetalation intermediate [Pd(Ph)(dppe)(PPh3)](BF4) and characterization by X-ray analysis. The reaction of a series of para-substituted arylboronic acids with 4a showed a slightly negative ρ value (−0.54), demonstrating an electronic effect that was accelerated by the donating substituents.

[reaction: see text]. In contrast to the Pd(0)-catalyzed mechanism by Uemura, Mizoroki-Heck type reaction of boronic acids is found to proceed under a Pd(II)-mediated pathway using a catalytic amount of Pd(OAc)2 in the presence of Cu(OAc)2 as an oxidant. Treatment of a variety of alkenes with boronic acids, boronates, and sodium tetraphenylborate furnishes beta-arylated and alkenylated products in good to excellent yields. The reactions with norbornene, norbornadiene, and diphenylacetylene are also performed to give 1:2 or 2:1 coupling products.

PdII-catalyzed Fujiwara-Moritani reactions can be carried out without external acid at room temperature, and in water as the only medium. A highly active cationic PdII catalyst, [Pd(MeCN)4](BF4)2, easily activates aromatic C-H bonds to produce electron-rich cinnamates in good yields.

Cationic palladium(II) catalyst realized facile C-H activation of aryl urea with arylboronic acids at room temperature. This reaction is extremely mild to carry out aromatic C-H activations through electrophilic substitution.