Diels–Alder Cycloadditions of 1,2-Dihydrophosphinine Oxides and Fragmentation-Related Phosphorylations with 2-Phosphabicyclo[2.2.2]Octadiene Oxides Under Green Chemical Conditions—The Role of Microwave and Ionic Liquids

Abstract

R 2 P Y O Cl R 1 P R 2 O Y Cl R 1 + P Y Me O O R 2 P Y O Cl R 1 CO 2 Me CO 2 Me + OH R R R 1 R 2 H Me Me H Y = Ph, EtO R = Me, H Abstract The effect of the use of microwave (MW) and solvents including ionic liquids on the Diels-Alder reaction of 1,2-dihydrophosphinine oxides (1) and fragmentation-related phosphorylation of phenols with 2-phosphabicyclo[2.2.2]octadiene oxides (4) was studied. The MW-assisted Diels-Alder reaction of dihydrophosphinine oxides (1) with N-phenylmaleimide may be advantageous to carry out in [bmim][BF 4 ] due to shorter reaction times, but the dimerization of the double-bond isomers (A and B) of the dihydrophosphinine oxides (1) may be best accomplished under MW in the absence of any solvent. The fragmentation-related phosphorylations may also be carried out under MW, which with the P-phenyl precursor (4a) became more efficient in [bmim][BF 4 ].

The Use of MW in Organophosphorus Chemistry

“…It was found that the fragmentation-related phosphorylations are more efficient under MW conditions using ionic liquids as the solvent. The phosphorylated phenols (69) were obtained in somewhat better yields than in earlier experiments (Scheme 3.46) [90]. …”

The Impact of Microwaves on Organophosphorus Chemistry

“…It was found that the fragmentation‐related phosphorylation is more efficient under MW conditions using ionic liquids as the solvent. Experiments showed that the phosphorylated phenols were obtained in somewhat better yields than in earlier experiments (Scheme /(2)) …”

Application of Microwave Irradiation in the Synthesis of P-Heterocycles

“…(24) and -octadiene (25) derivatives may be regarded precursors of low-coordinated fragments, as on thermal or photochemical effect, the bridging YP(O)CH 2 moiety is ejected that phosphorylates the nucleophile (alcohol, phenol, or amine) added to the mixture prior to fragmentation [47]. It was found that an ionic liquid (e.g., [bmim][BF 4 ]) as the reaction medium was advantageous (Scheme 9) [50]. In our experiments, 2-phenyl-2-phosphabicyclo[2.2.2]octadiene (25) was used as precursor, and phenols as the trapping agents.…”