Kyle Pearce

The mechanochemical technique of ball milling has been applied to the solventless and eco-friendly synthesis of chalcogenides (sulfide and selenide) of a variety of tertiary and aminophosphines. In most of the cases, the products are obtained in almost quantitative yields with high purity by applying a simple workup procedure without using chromatographic techniques or any other purification methods. The scope of this methodology was explored by using a range of phosphines (mono, di and tetra) to synthesize partial as well as mixed chalcogenides. The use of almost equimolar amounts of starting materials and the absence of any byproducts significantly simplifies the product isolation compared with the standard solution state reactions, thus providing a highly atom economic (100 %) method with an ideal E-factor (E = 0). The solid-state reactions were monitored by ³¹P{¹H} NMR spectroscopy. The structures of some of the products are also confirmed by single-crystal X-ray analyses. Although most of the reactions were carried out on ca. 100-mg scale, the scaling up of the reaction did not affect the course of the reaction.

This paper describes the prepartion of chalcogenides and partially oxidized derivatives of tertiary phosphines, amino- and a vareity of bisphosphines in almost quantitative yields under solvent free conditions using a rotary ball mill. The short duration, absence of solvents and lower rotation frequency make it an environmentaly benign and energy saving method.

The synthesis and characterization of a stable phosphaethynolatoborane, [B]OCP (1, [B]=N,N′-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), is described. The increased triple bond character of the P−C bond in 1 relative to the free ion (PCO⁻) is probed in a series of reactivity studies. Compound 1 readily dimerises in donor solvents to afford a cyclic five-membered 6π-aromatic compound, cyclo-P₂{C[B]}O{CO[B]} (2), which decarbonylates on UV irradiation. By contrast the nickel-mediated dimerisation of 1 affords the isomeric diphosphacyclobutene [P(CO[B])]₂. When 1 is reacted with organolithium reagents such as MesLi (Mes=2,4,6-trimethylphenyl), the boryl moiety shifts and the formation of the lithoxy-boryl-phosphaalkene [LiOC[B]P(Mes)]₂ was observed. The reactivity of this species towards electrophiles is also described.

BOCParty: The synthesis, characterization, and reactivity of a stable phosphaethynolatoborane, [B]OCP (1, [B]=N,N′-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), is described.

A new method for the iodine-catalyzed reduction of phosphine oxides with phosphites at room temperature is reported. The mild reaction conditions, scalability, and simple purification requirements render it a method of choice for the large-scale production and facile regeneration of a variety of phosphines. Mechanistic studies, supported by DFT calculations of the oxygen transfer between the starting phosphine oxide and the phosphite reagent, are also presented. Such transmutations of phosphorus species were previously unknown.

The facile reduction of phosphine oxides to phosphines can be achieved with inexpensive phosphites at room temperature. The mild reaction conditions, scalability, and simple purification requirements render this process a method of choice for the large-scale production and regeneration of a variety of phosphines.