Solid-liquid phase C-alkylation of active methylene containing compounds under microwave conditions

The solid–liquid phase C-alkylation of active methylene containing compounds with C=O or P=O functions under phase transfer catalysis or microwave conditions has been summarized in this minireview. The mono- and dialkylation of the methylene containing derivatives was investigated under microwave (MW) conditions. It was found that in many cases, there was no need to use phase transfer catalyst under MW conditions. Moreover, most of the reactions were carried out without any solvent. These results mean a serious green chemical advantage. © 2015 by the authors; licensee MDPI, Basel, Switzerland

Microwave-assisted solid-liquid phase alkylation of naphthols

Abstract: The microwave promoted alkylation of 1- and 2-naphthols with benzyl, butyl, ethyl and isopropyl halides in the presence of an alkali carbonate may result in O- and C-alkylated products. The alkylations were O-selective in the presence of K2CO3 in acetonitrile as the solvent and in the absence of phase transfer catalyst. The alkylations utilizing butyl and ethyl halides were also O-selective in solventless accomplishment and in the presence of triethylbenzylammonium chlorid

O-Arylation of Iodophenols with 2-Fluorobenzaldehyde Under Microwave Conditions

The arylation of 4-iodo-, 2-iodo- and 3-iodophenols with 2-fluorobenzaldehyde may be carried out in the presence of K2CO3 in DMF as the solvent under microwave conditions. The arylation of 4-iodophenole was promoted by the use of triethylbenzylammonium chloride (TEBAC) as the phase transfer catalyst. In the other model reactions, the use of TEBAC was harmful. By-products formed by isomerization and disproportionation were also detected

Multicomponent Synthesis of Potentially Biologically Active Heterocycles Containing a Phosphonate or a Phosphine Oxide Moiety

Several multicomponent synthetic approaches were elaborated for plenty of novel nitrogen or oxygen heterocycles containing a phosphonate or a phosphine oxide moiety. All multicomponent reactions were optimized through a model reaction in respect of the heating mode, molar ratio of the starting materials, atmosphere, catalyst, temperature, reaction time and solvent applied, and then, the extended preparation of small libraries of structurally-related compounds was performed. Most of the reactions could be considered as “green syntheses”, as they were carried out in the absence of any catalyst and/or solvent using microwave (MW) irradiation or even at ambient temperature. The scaling-up of a MW-assisted synthesis was also elaborated in a continuous flow MW system. Altogether more than 150 heterocyclic organophosphorus compounds were synthesized, among them several derivatives showed moderate or promising activity against the HL-60 cell line and Bacillus subtilis bacteria

Synthesis of α-aminophosphonates by the Kabachnik–Fields reaction and by the Pudovik reaction

α-Aminophosphonates are of significant importance due to their biological activity. The most widely applied synthetic routes towards α-aminophosphonates are the Kabachnik-Fields reaction involving the condensation of amines, oxo compounds and >P(O)H species, such as dialkyl phosphites, and the Pudovik reaction of imines and >P(O)H reagents. By the double Kabachnik-Fields reaction, bis(aminophosphonates) have also became available. This chapter summarizes the synthesis of α-aminophosphonates and related derivatives through the two main routes as described in the literature over the last five years

Application of the Microwave Technique in Continuous Flow Processing of Organophosphorus Chemical Reactions

The microwave (MW) technique is an efficient tool in the realization of organic reactions, as well as in the analytical field and in the food industry. The continuous flow approach is of special interest as a promising way to scale-up MW-assisted syntheses. Besides summarizing the batch precedents, this review focuses on the utilization of the MW technique in the continuous-flow realization of organophosphorus transformations. The advantages of the continuous flow technique against the batch accomplishment are also shown. A few materials chemistry-related applications are also mentioned

Microwave-assisted synthesis of α-aminophosphonates with sterically demanding α-aryl substituents

A series of N-benzhydryl protected α-aminophosphonates with α-phenyl, α-(1-naphtyl), α-(9-anthryl) or α-(1-pyrenyl) substituents was synthesized by the Kabachnik–Fields condensation of diphenylmethylamine (benzhydrylamine), the corresponding aryl aldehyde and a dialkyl phosphite under MW irradiation. X-ray studies performed at low temperatures for a few of these α-aminophosphonates confirmed the presence of unusually short intramolecular Cα–Hδ+ ··· δ+H–Cperi contacts