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• 108-91-8 cyclohexylamine 
• 87243-93-4 1-hydroxy-3-methyl-3-phospholene 1-oxide 
• 18874-22-1 1-chloro-3-methyl-3-phospholene-1-oxide 

Relevant academic research and scientific papers

Direct estirification and amidation of phosphinic acids under microwave conditions

Phosphinic acids may be efficiently esterified in microwave-assisted reactions with alcohols. Especially alcohols with longer alkyl chain are suitable reagents for direct esterifications. At the same time, the direct amidation cannot be complete under such conditions. Hence, the tradional amidations via the phosphinic chloride intermediates have to be applied. The values of activation enthalpies and reaction enthalpies obtained by quantum chemical calculations justified the experimental observations. Microwave has a potential in overcoming relatively high activation enthalpies.

T3P-assisted esterification and amidation of phosphinic acids

A few phosphinic acids, such as phenylphosphinic acids, 1-hydroxy-3-phospholene 1-oxides and 1-hydroxyphospholane oxides are esterified with simple alcohols in the presence of propylphosphonic anhydride (T3P). If 1.1 equiv of the T3P reagent is used, the esterifications are fast and efficient at 25° C. In the case of more reactive models it was enough to apply 0.66 equiv of T3P at 85°C under microwave conditions. The amidation of 1-hydroxy-3-methyl-3-phospholene oxide could also be accomplished under similar conditions.

Microwave-assisted functionalization of phosphinic acids: Amidations versus esterifications

Both the reaction enthalpies and enthalpies of activation obtained by high-level quantum chemical calculations were against the direct amidation of phosphinic acids under traditional thermal conditions. However, the amidations, not expected to proceed on the basis of the endothermicity and the significantly high enthalpies of activation, did take place under microwave (MW) conditions in 30-36% conversions. As a comparison, the direct esterifications of phosphinic acids that are thermoneutral and have higher enthalpies of activation were quite efficient under MW conditions. The outcome of the MW-assisted amidation is the balance of two effects. The local overheating effect could overcome the barrier meant by the enthalpy of activation, but the endothermicity works against this. Comparison of the results of the syntheses and the energetics calculated for the esterification and amidation of phosphinic acids enabled us to draw more general conclusions on the scope and limitation of the use of MW irradiation in organic syntheses. The traditional amidation of phosphinic acids via the phosphinic chloride intermediate gave the products in much better yields. 2013 Wiley Periodicals, Inc. Heteroatom Chem 24:91-99, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21068

Synthesis of 1-Amino-2,5-dihydro-1H-phosphole 1-oxides and their N-phosphinoyl derivatives, bis(2,5-dihydro-1 H -phosphol-1-yl)amine P, P-dioxides

Depending on the molar ratio of the reactants and on the order of mixing, the reactions of a series of primary amines with 1-chloro-2,5-dihydro-1H- phosphole 1-oxides prepared in situ from the corresponding hydroxy- dihydrophosphole oxides afforded 1-amino-2,5-dihydro-1H-phosphole 1-oxides, or their N-phosphinoyl derivatives, bis(2,5-dihydro-1H-phosphol-1-yl)amine P,P-dioxides. The latter family of P-heterocycles could also be synthesized by the reaction of 1-amino-2,5-dihydro-1H-phosphole oxides with chloro-dihydrophosphole oxides.