Kinetics and mechanism of the Pudovik reaction in the azomethine series: III. Acid-catalyzed hydrophosphorylation of imines
摘要:
A complex spectral (UV, IR, and P-31 NMR), preparative, and kinetic investigation of the mechanism of the noncatalytic variant of the Pudovik reaction in the series of imines was carried out. The reaction proceeds through a four-center cyclic transition state. The transition state is highly labile, which determines its high sensitivity to the structure of the reagents, the nature of the solvent and catalyst, and some other factors. The necessary condition for the hydrophosphorylation of imines to occur is the participation of proton-donor reagents and acidic admixtures, specifically hydrolysis products of dialkyl hydrogen phosphites, such as monoalkyl dihydrogen phosphates and phosphorous acid, which act as acid catalysts. When the starting, reagents are thoroughly purified and no such catalysts are present, the Pudovik reaction fails to occur in the imine series.
Zirconium(IV) Compounds As Efficient Catalysts for Synthesis of α-Aminophosphonates
作者:Srikant Bhagat、Asit K. Chakraborti
DOI:10.1021/jo8009006
日期:2008.8.1
Zirconium(IV) compounds are reported as excellent catalysts for a three-component one-pot reaction of an amine, an aldehyde or a ketone, and a di/trialkyl/aryl phosphite to form α-aminophosphonates under solvent-free conditions at rt. Among the various zirconiumcompounds, ZrOCl2·8H2O and ZrO(ClO4)2·6H2O were most effective. The reactions were faster with dialkyl/diaryl phosphites than with trialkyl/triaryl
An Extremely Efficient Three-Component Reaction of Aldehydes/Ketones, Amines, and Phosphites (Kabachnik−Fields Reaction) for the Synthesis of α-Aminophosphonates Catalyzed by Magnesium Perchlorate
作者:Srikant Bhagat、Asit K. Chakraborti
DOI:10.1021/jo062140i
日期:2007.2.1
an extremely efficient catalyst for the synthesis of α-aminophosphonates. A three-component reaction (3-CR) of an amine, an aldehyde or a ketone, and a di-/trialkyl phosphite (Kabachnik−Fields reaction) took place in one pot under solvent-free conditions to afford the corresponding α-aminophosphonates in high yields and short times. The use of solvent retards the rate of the reaction and requires a