Novel synthetic method for N-heterocyclic carbene transition metal complexes and new green catalytic applications [electronic resource]

9781109200256

2009

1 online resource (137 p.)

Access is available to the Yale community

Access is restricted by licensing agreement.

The development of safer, more atom economical catalytic reactions and catalyst syntheses is an important goal of green chemistry. In Chapter 2, a novel approach for the green and efficient synthesis of transition metal N-heterocyclic carbene complexes from N,N'-disubstituted imidazolium carboxylates via release of CO2 is presented. This method efficiently affords previously reported and novel NHC complexes of Rh, Ir, Ru, Pt and Pd and avoids the use of strong bases. Tuning the reaction conditions for NHC transfer can give selectively either mono- or bis-NHCs, or bis- and tris-NHC metal complexes. Computational studies elucidate the mechanism of the reaction forming from N,N'-disubstituted imidazolium carboxylates from with (MeO)2CO and N-methylimidazole, and also the NEC transfer step to the metal precursor. The concept of loss of CO2 led in Chapter 3 to the exploration of decarboxylative coupling strategies for making biaryls from benzylic acids and either aryl halides via C-X activation, or unactivated aromatics by C-H activation. We show that microwave heating improves the efficiency of this reaction, and allows the use of benzoic acids which were previously considered to be underactive for decarboxylation. In Chapter 4, a novel iridium-catalyzed C-H activation and functionalization of simple arenes affords aldehydes, esters, and imines in the presence of Ag2CO3 as base and oxidant. A catalytic reaction capable of selective partial reduction of quinoline derivatives using phenyl silane as the reductant is shown to obliterate the need for stoichiometric lithium reagents, which were previously known as the only synthetic route to these compounds. Finally, in Chapter 5, a catalytic strategy for synthesizing amides, functional groups which are typically prepared using toxic stoichiometric reagents, such as thionyl chloride, is presented. It utilizes amines and aldehydes, which when condensed to imines, can oxidized catalytically to oxaziridines. The oxaziridines are and in turn rearranged catalytically to afford the amide.

Books / Online / Dissertations & Theses

English

July 12, 2011

Thesis (Ph.D.)--Yale University, 2009.

Yale University.