Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products

The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.

Novel and durable flame-retardant modification based on the Schiff base and Pudovik reaction for wool fabric

Durable and formaldehyde-free flame-retardant (FR) modification of wool fabric using phosphorous compounds is of great interest. In this study, Schiff base imine groups were firstly introduced onto wool fiber through aldehyde-amine condensation between p-hydroxybenzaldehyde and wool fiber. Then, an efficient and durable FR wool fabric was fabricated by incorporating diethyl phosphite (DEP) into a Schiff base intermediate via the Pudovik reaction. The potential reaction mechanism among p-hydroxybenzaldehyde, DEP and wool fiber was explored. The thermal stability, smoke generation ability, FR ability and washing durability of the modified wool fabric were studied. The FR modification significantly increased the thermal resistance of wool fabric and suppressed smoke generation by half. The wool fabric modified by 20 g/L DEP was able to self-extinguish during the burning test, suggesting the higher FR efficiency of the DEP-incorporated Schiff base system. The modified wool fabric still self-extinguished after 20 commercial launderings, which is attributed to the covalent grafting of DEP onto wool fiber. Char residue analyses revealed the condensed charring FR mechanism of the DEP-incorporated Schiff base system on wool. This work provides a novel approach to prepare efficient and durable FR functional wool fabric via the Schiff base reaction and Pudovik reaction among p-hydroxybenzaldehyde, DEP and wool fiber.

Practical Synthesis of 1,2,3,4-Tetrahydroisoquinoline-1-phosphonic and -1-phosphinic Acids through Kabachnik–Fields and Aza-Pudovik Reaction

We report here an alternative and practical method for the preparation of 1,2,3,4-tetrahydroisoquinoline-1-phosphonic acid and the first synthesis of 1,2,3,4-tetrahydroisoquinoline-1-H-phosphinic and 1,2,3,4-tetrahydroisoquinoline-1-phenylphosphinic acids through Kabachnik–Fields and aza-Pudovik reaction. This methodology does not require any metallic catalyst and proceeds under mild reaction conditions.

Synthesis of Phosphaproline Derivatives: A Short Overview

Pyrrolidine-based phosphonates, analogues of the natural amino acid proline, possess a diverse set of biological activity. The goal of this short review is to summarize the major developments in the synthesis of phosphaproline derivatives reported since 2004 with special emphasis on the mechanisms and limitations of the methods presented.1 Introduction2 Phosphorylation of Pyrrolidine Derivatives2.1 Syntheses via Pudovik Reaction2.2 Syntheses via Arbuzov Reaction2.3 Decarboxylative Phosphorylation of Proline2.4 Direct C–H Bond Phosphorylation2.5 Other Reactions2.6 Overview of Phosphorylation Methods3 Synthesis of 2-Phosphorylpyrrolidines from Acyclic Precursors3.1 Cyclization of 4-Substituted Butylamine Derivatives3.2 [3+2]-Dipolar Cycloaddition of α-Iminophosphonates3.3 Cyclization of Aminoalkynes and 4-Aminocarbonyl Compounds4 Conclusions