A few phosphinicacids, 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
Abstract 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 directamidation cannot be complete under such conditions. Hence, the tradional amidations via the phosphinic chloride intermediates have to be applied. The values of activation enthalpies
A study on the acidic hydrolysis of cyclic phosphinates: 1-Alkoxy-3-phospholene 1-oxides, 1-ethoxy-3-methylphospholane 1-oxide, and 1-ethoxy-3-methyl-1,2,3,4,5,6-hexahydrophosphinine 1-oxide
作者:György Keglevich、Zita Rádai、Nikoletta Harsági、Áron Szigetvári、Nóra Zsuzsa Kiss
DOI:10.1002/hc.21394
日期:2017.9
AbstractThe hydrochloric acid‐catalyzed hydrolysis of phosphinates was studied on 1‐alkoxy‐3‐phospholene 1‐oxides, 1‐ethoxy‐3‐methylphospholane 1‐oxide, and 1‐ethoxy‐3‐methyl‐1,2,3,4,5,6‐hexahydrophosphinine 1‐oxide as the model compounds. Under the conditions applied, the isomerization of the 3‐phospholene moiety to the 2‐phospholene ring also occurred leading to mixtures of the corresponding 1‐hydroxy‐3‐phospholene oxide and 1‐hydroxy‐2‐phospholene oxide. According to our optimized method, using 3 equivalents (0.5 mL) of concentrated hydrochloric acid in 1 mL of water per ca. 2 mmol of the substrate at reflux, the completion required 3‐10 hour. The hydrolyses were characterized by pseudo‐first‐order rate constants and the isomerizations by rate constants. The application of p‐toluenesulfonic acid under microwave irradiation at 140°C in the hydrolysis of 1‐alkoxy‐3‐methyl‐3‐phospholene oxides associated with reaction times of 1‐3 hour. The reactivity order of the 5‐ and 6‐ring phosphinates in hydrolysis was set up.