Synthesis of New Cα,α-Diarylaminomethylphosphonic Acids and their Esters

Abstract

A procedure for the preparation of N-protected 1 or unprotected C_a,a-disubstituted (diarylaminomethyl)-phosphonic acids and their esters is reported.¹ This method is a generalisation of the Kabachnik-Fields method described in the literature.²     

Umpolung of α-Allenic Ketones and Esters by Phosphorus Groups

Abstract

Change in the regioselectivity of the addition of nucleophilic compounds YH (ROH, RSH, RNH₂) on α -allenic ketones and esters can be achieved by using the triphenylphosphonio group as an umpolung agent¹⁾. In this way α, β-unsaturated ketones and esters 4 are obtained with heteroatomic substituents in the γ position. The Umpolung scheme of the activated allene 1 is charaterized by a functional vinylphosphonium salt 2 as a synthetic equivalent of the a⁴-synthon 3.     

Homologation of α,β-Ethylenic Ketones in Substituted β,γ-Ethylenic Ketones Using Phosphoniosilylation

Among the methods described (1–4) to prepare β,γ-unsaturated ketones 2, Warren (4) recommends the Wittig-Horner procedure involving β-acetalated diphenylphosphinoxides reagents |scheme 1 (i)|.     

Reaction of lithium diphenylphosphonium di(methylide) with carbonic acid derivatives. A novel access to polyfunctional unsaturated esters and amides

The lithium diphenylphosphonium di(methylide) Ph₂ P(CH₂)₂ Li 1 readily attacks cyclic carbonates, carbamates, and thiocarbamates, resulting in “pseudo-acylation” products, after a ring-opening step. Thus, new stabilized ylides are prepared, which can be used in situ as carbonyl olefination reagents towards aldehydes. This procedure is a new one-pot method for the synthesis of (E)-vinylic esters and amides, bearing a free ω-hydroxyl group. When a thiocarbamate is the initial substrate for 1 , a Michael-type cyclization occurs, following the Wittig olefination, resulting in the one-pot preparation of 7-membered heterocycles.     

Toxic organophosphorus esters hydrolysis enhanced by onium perborates

The addition of equimolecular quantities of phosphonium salts to an aqueous sodium perborate solution (Na⁺ PB⁻) greatly enhances he efficiency of Na⁺ PB⁻ as a reagene that destroys organophosphorus esters, such as p-nitrophenyldiethyl phosphate or ethyl p-nitrophenyl methylphosphonate.     

Synthesis of (poly)alkoxymethylphosphine oxides by classical and phase transfer catalyzed Williamson reactions

(Poly)alkoxymethylphosphine oxides were synthesized by the Williamson reaction starting from (poly)hydroxymethyl or (poly)chloromethyl‐phosphine oxides. For the first time, the use of phase transfer catalysis for the synthesis of (O)PCOC bridges is demonstrated.© 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 307–311, 1999     

Destruction of chemical warfare agents VX and soman by α‐nucleophiles as oxidizing agents

Reactions of O‐ethyl S‐(2‐diisopropyl‐amino)ethyl methylphosphonothiolate, VX 1 , were investigated with five oxidizing agents. In all the cases, the formation of the VX N‐oxide 7 was observed prior to the subsequent oxidation and hydrolysis into the nontoxic O‐ethyl methylphosphonate 2. Magnesium monoperoxyphthalate (MMPP) is probably one of the most active reagents to achieve the complete detoxification of VX 1 . The decontamination using MMPP was also extended with success to soman 13 , a G‐type agent. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:485–490, 2001