Microwave-assisted alkylation of diethyl ethoxycarbonylmethylphosphonate under solventless conditions

Application of the Microwave Technique in Continuous Flow Processing of Organophosphorus Chemical Reactions

The microwave (MW) technique is an efficient tool in the realization of organic reactions, as well as in the analytical field and in the food industry. The continuous flow approach is of special interest as a promising way to scale-up MW-assisted syntheses. Besides summarizing the batch precedents, this review focuses on the utilization of the MW technique in the continuous-flow realization of organophosphorus transformations. The advantages of the continuous flow technique against the batch accomplishment are also shown. A few materials chemistry-related applications are also mentioned.

Microwave irradiation and catalysis in organophosphorus reactions

The usual advantage of microwave (MW) assistance is making organic reactions faster and more efficient. In this article we present reaction types from organophosphorus chemistry, when MW-assisted transformations (e.g. the direct esterification and alkylating esterification of phosphinic acids) may be promoted by suitable catalysts, or vice versa, when a catalytic reaction is enhanced by MW irradiation (e.g. the Arbuzov reaction of aryl halides), and when catalysts may be omitted or simplified under MW irradiation as shown by the alkylation of active methylene containing P=O substrates/the Kabachnik–Fields reaction/deoxygenation of phosphine oxides, and the Hirao reaction, respectively.

Microwave-assisted alcoholysis of dialkyl phosphites by ethylene glycol and ethanolamine

A study on the microwave-assisted alcoholysis of diethyl phosphite with ethylene glycol revealed that after optimization of the conditions (molar ratio, temperature and time), the target “monomer,” (HOCH2CH2O)2P(O)H was formed in a proportion of 59 %, but with an incomplete conversion. The formation of the (HOCH2CH2O)(EtO)P(O)H and H(EtO)(O)POCH2CH2OP(O)(OEt)H by-products was, in most cases, inevitable. The alcoholysis with ethanolamine was more efficient and took place in a conversion of 100 % to afford H2NCH2CH2O)2P(O)H in a proportion of 85 %. An alkyl substituent on the N-atom prevented the alcoholysis.

A “green” variation of the Hirao reaction: the P–C coupling of diethyl phosphite, alkyl phenyl-H-phosphinates and secondary phosphine oxides with bromoarenes using a P-ligand-free Pd(OAc)2 catalyst under microwave and solvent-free conditions

The general value of the title reaction affording diethyl arylphosphonates, alkyl diphenylphosphinates and tertiary phosphine oxides was demonstrated.