Investigations on 1,2σ³λ³-Oxaphosphetanes

Abstract

In this thesis, new 1,2σ³λ³-oxaphosphetanes were synthesis and the reactivity of this former elusive compound class was investigated. This work describes the synthesis of 1,2σ³λ³-oxaphosphetanes by reacting their corresponding pentacarbonyl molybdenum complexes with a chelating ligand. A breakthrough was the synthesis of a C-unsubstituted 1,2-oxaphosphetane. The investigated reactions of 1,2σ³λ³-oxaphosphetanes can be divided in three main topics: In the first part, the synthesis of 1,2-oxaphosphetane chalcogenides was achieved by reaction with an oxygen transfer reagent or by reaction with the elements sulfur and selenium. Also, the synthesis of the first borane·1,2-oxaphosphetane complexes. In the second part, a series of Arbuzov reactions was performed, yielding selectively the expected β-haloethylphosphane oxide compounds. The reaction with less nucleophile methyl triflate led to the formation of oligomers. To broaden the scope of the reaction, the 1,2-oxaphosphetanes was reacted with halogens. The reactions with bromine and iodine were highly selective and formed the corresponding halo(2-haloethyl)phosphane oxides in an Arbuzov-like mechanism. The third part of this work is concerned with the reaction of 1,2-oxaphosphetanes with acetic and hydrochloric acid. The reactions were unselective and four main products were observed in each case. Through a combination of NMR spectroscopic data and quantum chemical computations a structure proposals were made for all products and a feasible reaction pathway constructed.