82134-81-4Relevant academic research and scientific papers
The Acylation of Neutral Phosphoramidates
Challis, Brian C.,Iley, James N.
, p. 1489 - 1494 (2007/10/02)
Kinetic studies of the acylation of neutral secondary phosphoramidates by acid halides and anhydrides are reported.The reactions produce both N-acylphosphoramidates and carboxamides by cleavage of the P-N bond.The extent of the carboxamide formation varies with the strngth of the acid co-product and with steric and electronic factors associated with both the acylating agent and the nitrogen substituent of the phosphoramidate.Except for pivaloyl chloride, the presence of a base diminishes the amount of carboxamide formed.With either acid halides or anhydrides tertiary phosphoramidates produce carboxamides directly.The formation of both N-acylphosphoramidate and carboxamide follow the equation: rate = k2 .Second-order rate constants, k2, for the formation of N-acylphosphoramidates vary with the structure of the acylating agent: AcBr is 18 times more reactive than AcCl; in solvent pyridine the Hammett ρ-value for substituted benzoyl chlorides is 1.8; in solvent CCl4 Taft ρ* and δ values for substituted acid chlorides are 0.7 and 0.76 respectively.These data are best interpreted in terms of a bimolecular substitutions reaction involving nucleophilic attack by the phosphoramidate nitrogen atom at the carbonyl carbon of the acylating agent to form an N-acylphosphoramidate cation (5).Breakdown of this cation can give either the N-acylphosphoramidate via deprotonation, or the carboxamide via P-N bond cleavage.Carboxamide formation is favoured for reactions where P-N bond cleavage either relieves steric strain or the carboxamide is a good nucleofuge.Catalysis of the reaction between phosphoramidates and acetic anhydride by electrophiles such as AcX and HX is shown to involve acylation by AcX followed by a rapid re-formation of AcX from Ac2O and HX.
PHOSPHORIC-CARBOXYLIC IMIDES. III. THE BENZOYLATION OF N-METHYLDIETHYLPHOSPHORAMIDATE AND RELATED ANIONS
Hendrickse, Theodore F.,Mizrahi, Valerie,Modro, Tomasz A.
, p. 93 - 106 (2007/10/02)
The synthetic route to mixed phosphoric-carboxylic imides (1) via the N-acylation of phosphoramidates was investigated.The reaction of PhC(O)X(X = Br, Cl, F) with conjugate base of (EtO)2P(O)NHMe (2) yields three products: PhCO2Et (3), PhC(O)NHMe (4) and (PHCO)2NMe (5). (4) and (5) are formed via the initial rapid formation of (1), while (3) results from the ElcB raction of (2).The attack of various nucleophilic species at mixed imide (1) was studied, and the possible mechanisms of the P-N bond cleavage, followed by the transfer of nitrogen from phosphoryl to the carbonyl centre, are discussed.
Phosphoric Carboxylic Imides. 1. Preparation and Fragmentation Behavior of Dialkylphosphoryl (and Phosphinyl) Acetyl (and Benzoyl) Imides and Related Systems
Mizrahi, Valerie,Modro, Tomasz A.
, p. 3533 - 3539 (2007/10/02)
Six phosphoric carboxylic imides X2P(O)-NR-C(O)R' (I,X = MeO, EtO, Et; R = H, Me; R' = Me, Ph) were synthesized and characterized.Mass spectra of compounds I were recorded, and the observed fragmentation behavior is compared with that of phosphoric amides X2P(O)NHR and carboxylic amides R'(O)NHR reported in the literature and obtained in this work.The main pathways of fragmentation of the imides I indicate that the molecular ions involve mainly the radical cationic center at the carbonyl oxygen.All imides give products resulting from the fragmentation following theinitial isomerization of substrates to the corresponding O-phosphoryl (or phosphinyl) imidates X2P(O)-O-C(NR)R'.Under recording conditions, tertiary substrates (I, R = Me) undergo (70 eV, 200 deg C) reaction, yielding the corresponding tetraalkyl pyrophosphates (RO)2P(O)OP(O)(OR)2, which give rise to new peaks in the mass spectra.For the O-ethyl derivatives (I, X = OEt), structural features favoring the loss of ethylene (McLafferty rearrangement) or the loss of the vinyl radical (double hydrogen rearrangement) are discussed.
