Recyclable Heterogeneous Palladium Catalysts in Pure Water: Sustainable Developments in Suzuki, Heck, Sonogashira and Tsuji-Trost Reactions

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki-Miyaura reactions

A diphenylphosphinite cellulose palladium complex (Cell–OPPh₂–Pd⁰) was found to be a highly efficient heterogeneous catalyst for the Suzuki–Miyaura reaction. The products were obtained in good to excellent yield under mild reaction conditions. Moreover, the catalyst could be easily recovered by simple filtration and reused for at least 6 cycles without losing its activity.

Nanoparticulate Pd supported catalysts: size-dependent formation of Pd(I)/Pd(0) and their role in CO elimination

A combination of time-resolved X-ray absorption spectroscopy (XAS), hard X-ray diffraction (HXRD), diffuse reflectance infrared spectroscopy (DRIFTS), and mass spectrometry (MS) reveals a series of size-dependent phenomena at Pd nanoparticles upon CO/(NO+O(2)) cycling conditions. The multitechnique approach and analysis show that such size-dependent phenomena are critical for understanding Pd CO elimination behavior and, particularly, that different Pd(I) and Pd(0) centers act as active species for a size estimated by XAS to be, respectively, below and above ca. 3 nm. The relative catalytic performance of these two noble metal species indicates the intrinsic higher activity of the Pd(I) species.

RuCl3·3H2O Catalyzed Tandem Reaction of Alkynylbromides with 2-Aminothiophenols in Water: A Convenient Synthesis of 2-Benzoylbenzothiazoles

RuCl3·3H2O catalyzed tandem reaction of alkynyl bromides with 2-aminothiophenols mediated by water is shown to represent a convenient synthesis of 2-benzoylbenzothiazoles. In addition, the Ru(iii) catalyst could be readily recovered and efficiently reused together with water up to three times.

Palladium-catalyzed oxidative arylhalogenation of alkenes: synthetic scope and mechanistic insights

This article describes the development of a Pd-catalyzed reaction for the arylhalogenation (halogen = Cl or Br) of diverse alpha-olefins by oxidatively intercepting Mizoroki-Heck intermediates. These transformations afford synthetically useful 1,2- and 1,1-arylhalogenated products in good yields with good to excellent selectivities that can be modulated by changing the nature of the halogenating reagent and/or the reaction conditions. The selectivity of these reactions can be rationally tuned by (i) controlling the relative rates of oxidative functionalization versus beta-hydride elimination from equilibrating Pd(II)-alkyl species and (ii) stabilization of organometallic Pd(II) intermediates through the formation of pi-benzyl adducts. These arylhalogenations exhibit modest to excellent levels of stereoselectivity, and the key carbon-halogen bond-forming step proceeds with predominant retention of stereochemistry at carbon.