A FACILE SYNTHESIS OF DIETHYL 1- ISOTHIOCYANO)ALKYLPHOSPHONATES[1]

Abstract

Novel, diethyl 1-(isothiocyano)alkylphosphonates 3 have been efficiently synthesized via a one-pot reaction of diethyl 1-azidoalkylphosphonates 1 with triphenylphosphine, followed by in situ transformation of thus formed phosphazenes 2 with carbon disulfide. Application of the title compounds in the synthesis of diethyl (N-phenylthioureido)- and (benzothiazol-2-ylamino)methylphosphonates was also described.     

A New Protocol for O-Methylation of Phenolic Compounds with Trimethyl Phosphite or Trimethyl Phosphate Under Solvent-Free Condition and Microwave Irradiation

A simple method for the preparation of industrially important alkyl aryl ethers is reported. Several phenolic compounds such as phenols, naphthols, and hydroxy coumarins were O-methylated with trimethyl phosphite or trimethyl phosphate under microwave irradiation and solvent-free condition in almost quantitative yields. Reaction of 2-naphthol with trimethyl phosphate gave mixture of 2-methoxynaphthalene and 1-methyl-2-methoxynaphthalene while the reaction with trimethyl phosphite gave mostly 2-methoxynaphthalene. This method is highly efficient for the methylating of phenolic compounds with very easy experimental procedure and environmental friendly conditions.     

NMR Characterization of Substituted Aromatic Poly (Ether Sulofone)s

Abstract

The synthesis of a variety of substituted bisphenol A polysulfones, including nitro, amino, aminomethyl, ethyl, and methyl derivatives, is described. Nuclear magnetic resonance (NMR) (both proton and carbon, and several 2-D experiments) data confirm conclusions on the substitution site based on arguments on inductive effects in the phenyl rings. The proton ortho to the oxygen in the bisphenol A (BPA) residue is replaced in electrophilic substitution reactions. The degree of substitution was also calculated from the NMR results. The ethyl and methyl derivatives were expected, from the starting reactants, to each have a BPA ring substituted. The NMR data showed that, on the average, this is true. The nitro derivative also has substitution in every BPA ring, while the amino and aminomethyl derivatives have only intermittent BPA rings substituted. Measured degrees of substitution (DS) varied from 0.11 to 2.25.     

PEG-600-mediated,green and efficient,tandem syntheses of N-subtituted-2-styrylquinazolin-4- ones

Polyethylene glycol (PEG)-mediated, green and efficient, tandem syntheses of N-subtituted-2-styrylquinazolinones are being reported. Condensation of anthranilamide (1) with acetic anhydride in PEG-600, at 100°C for 1 hr gave 2-methyl-3H-quinazoline-4-one (2). Treatment of 2 with benzaldehydes in PEG-600, at 100°C for 2–3 hr, gave 2-styrylquinazolinone-4-ones (3) in excellent yields. Treatment of 3 (a–d) either with dimethyl sulfate (DMS), diethyl sulfate (DES), or with Ph-CH₂-Cl, individually in PEG-600, at 100°C for 1–2 hr without using any base, followed by simple processing resulted in N-substituted-2-styrylquinazolin-4-ones 5 (a–l). In an alternative approach, reaction of 4 (a–c) with benzaldehydes in PEG-600, at 100°C for 1–2 hr, without using any base, followed by simple processing resulted in 5 (a–l). 4 (a–c) were prepared by treatment of 2 with either DMS, DES, or with Ph-CH₂-Cl, individually, in the presence of PEG-600 as reaction medium, at 100°C for 1–2 hr without using any base. Both the sequence of reactions, 1 2 3 5 or 1 2 4 5 could be carried out in tandem in an efficient manner in PEG-600 without the isolation of any intermediates. The structures of all the new compounds synthesized in this work have been established on the basis of their spectroscopic data and analytical data.     

Three-Component,One-Pot Synthesis of New Functionalized Pyrrolines

The addition of acetylenic esters to diethyl acetamidomalonate in the presence of tert-butyl isocyanide leads to highly functionalized 1-pyrrolines and 2-pyrroline.     

Studies of the Synthesis of Diethyl Cyclopropylphosphonate and Its Thio and Seleno Analogs

Two methods for the synthesis of unsubstituted diethyl cyclopropylphosphonate are described. One method is a reaction between cyclopropylmagnesium bromide and diethyl chlorophosphite to give diethyl cyclopropylphosphonite, followed by oxidation with sodium periodate to the corresponding phosphonate. Alternatively, diethyl cyclopropylphosphonite was reacted with elemental sulfur or selenium to give the thio and seleno analogs, respectively. The second method involves exclusive 1,3‐elimination of HBr from diethyl 3‐bromopropylphosphonate. This method can be directed to either the 1,2‐ or the 1,3‐elimination reaction, leading to propenylphosphonate or cyclopropylphosphonate, depending on the solvent used.     

Simple and Efficient One-Pot Synthesis of 2-Substituted Benzoxazole and Benzothiazole

2-Substituted benzoxazole and benzothiazole were synthesized from condensation of aldehyde and 2-aminophenol or 2-aminothiophenol via a one-pot process using diethyl bromo phoshonate and tert-butyl hypochlorite.     

Simple and Advantageneous Stereoselective Synthesis of (Z)-Allyl Phosphonates Starting from Baylis–Hillman Adducts

Baylis–Hillman adducts 3-hydroxyl-2-methylene alkanoates have been converted in one pot into the corresponding (Z)-allyl phosphonates by treatment with FeCl₃ and trialkyl phosphites in toluene under reflux. The products are formed in excellent yields (88–98%) within 1–1.5 h. The process is highly convenient and efficient, cost-effective, and remarkably stereoselective.     

ZrOCl2·8H2O: An Efficient Catalyst for One-Pot Synthesis of α-Amino Phosphonates Under Solvent-Free Conditions

A highly efficient protocol has been developed for the three-component reaction of an amine, an aldehyde, and diethyl phopshite catalyzed by ZrOCl₂·8H₂O, an environmentally friendly catalyst, at ambient temperature. The catalyst exhibited remarkable activity and tolerated a wide variety of functional groups, providing the desired amino phosphonates in excellent yields under solvent-free conditions. Alternatively, the reaction rate can be significantly enhanced by carrying out the reaction in a monomode microwave reactor as a promoter.     

A Double-Site Chemodosimeter for Selective Fluorescence Detection of a Nerve Agent Mimic

A novel two-site chemodosimeter (SWJT-4) based on fluorescein skeleton to detect diethyl chlorophosphate (DCP) was designed and synthesized. It is a turn-on fluorescent probe for DCP with good selectivity and obvious color change in aqueous solution. Interestingly, the two oxime groups of SWJT-4 as dual response sites initiated different reactions with DCP to form a cyano group and an isoxazole ring, respectively. The corresponding mechanism was confirmed by ¹H NMR, MS and DFT calculation. Moreover, SWJT-4 could be used as a fluorescent test paper to detect DCP vapor.