Date of Award

9-7-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Irina Smoliakova

Abstract

Aminophosphines, diphosphines and related chelating P-containing bidentate ligands, due to their versatile structural features, are considered promising enantioselective catalyst alternatives to symmetric and monodentate phosphine ligands. There are several methods for preparation of such P,N-ligands; however, they are mostly limited to specific cases. In this dissertation, the development of a new general method for synthesis of P-containing bidentate ligands is described. The approach studied is based on using reactions of cyclopalladated complexes (CPCs) with LiPPh2, KPPh2 and HPPh2. This study is the first example of a systematic investigation of reactions of CPCs at a C–Pd bond with phosphorus nucleophiles. A variety of structurally different CPCs containing different heteroatoms and chirality sources were obtained. Reactions of these CPCs with LiPPh 2, KPPh2 and HPPh2 were thoroughly studied under different conditions. General procedures of synthesis of P-containing bidentate ligands using reactions of CPCs with each of the phosphorus-containing reagents were developed. The structures of all new compounds obtained in the reactions were supported by spectroscopic methods and, in some cases, by X-ray crystallography. Purity and elemental composition of the synthesized complexes and organic compounds were confirmed by either satisfactory elemental analysis or high resolution mass spectra data. The reaction mechanisms were studied using variable temperatures 31P{1H} and 31P nuclear magnetic resonance (NMR) spectroscopy. A procedure for NMR monitoring of air- and moisture-sensitive reaction mixtures was developed. On the basis of the obtained experimental and literature data, the mechanisms of the reactions of CPCs with each of the reagents, LiPPh2, KPPh2 and HPPh2, were proposed. A possibility of using HPPh2 in Pd(II)-catalyzed reactions with N,N-dimethylbenzylamine and other substrates capable of cyclopalladation was shown. A catalytic cycle for this transformation was proposed.

Download

Share

COinS