Derivatization and Determination of MCPA in Soil by GC

A reliable and sensitive method for determination of MCPA in soil by derivatization through p-toluenesulfonic acid and 1,3-dichloro-2-propanol followed by gas chromatographic detection under ECD mode has been established. After treatment with hydrochloric acid, the soil samples were directly extracted without any clean-up with dichloromethane by vortexing. After derivatization and liquid–liquid extraction, the product was subjected to GC analysis. Under optimized conditions, recovery of MCPA reached 87–91%; intra- and inter-day precision values were recorded in the range 3.4–6.4% and 7.4–8.7%, respectively. Excellent linear relationship was observed within 0.1–10 μg mL^?1 (0.005–0.5 mg kg^?1) with linear correlation coefficient (R) of 0.9997. The LOD and LOQ were 0.001 and 0.0026 mg kg^?1, respectively, and the overall sensitivity for detection was found to be in the same range as with the conventional GC-MS technique.     

Synthesis and antiviral activity of novel pyrazole amides containing α‐aminophosphonate moiety

A series of novel pyrazole amides J1 , J2 , J3 , J4 , J5 , J6 , J7 , J8 , J9 , J10 , J11 , J12 , J13 , J14 , J15 containing an α‐aminophosphonate moiety were synthesized and subsequently characterized by spectral (IR, ¹H‐, ¹³C‐, ³¹P‐, and ¹⁹F‐NMR) data and elemental analysis. The racemic sample of J1 was further separated into its enantiomers under normal‐phase condition on two immobilized polysaccharide‐based chiral stationary phases (Chiralpak IA and Chiralpak IC). The synthesized compounds revealed certain degree of antiviral activity in the bioassay. The title compounds ( J3 , J10 , and J12 ) showed some curative activities (39.9%, 41.8%, 50.1%, respectively) against tobacco mosaic virus at 0.5 mg/mL. J. Heterocyclic Chem., 00 , 00 (2011).     

Asymmetric Mannich reactions catalyzed by cinchona alkaloid thiourea: enantioselective one-pot synthesis of novel β-amino ester derivatives

An efficient one-pot synthesis of novel β-amino ester derivatives containing a benzoxazol moiety has been developed by using cinchona alkaloid thioureas as the organocatalyst. The adducts were isolated in high enantiomeric excess and high yield.     

Organocatalytic Application of Enamine Intermediate and Hydrogen Bonding Interaction to Dissymmetric Transformation

Interaction of enamine intermediate of primary or secondary amine with carbonyl compound and formation of hydrogen bonds with electronegative atoms are often responsible to activate a nucleophile or electrophile to enhance enantio- and diastereoselectivity in typical organocatalytic asymmetric transformations. The review lists some suitable applications of enamine intermediate and hydrogen bonding interaction in asymmetric organocatalysis.     

Analytical and semi-preparative enantioseparation of organic phosphonates on a new immobilized amylose based chiral stationary phase

Two chiral stationary phases derived from derivatized amylose (Chiralpak AD-H and Chiralpak IA) have been used to separate the enantiomers of new diethyl benzamidoarylmethylphosphonates. The data obtained indicate that all the studied compounds could be easily baseline resolved on both columns. Owing to the different techniques involved in their preparation, the two stationary phases differ in their abilities to effect enantiomeric separation. The semi-preparative separation of all compounds was executed successfully in n-hexane/EtOH on the new immobilized Chiralpak IA column. The analytical assessment of the enantiomeric excess values of all collected fractions was higher than 97%. The stereochemical configuration for the F1 fraction of a diethyl benzamidoarylmethylphosphonate was determined by X-ray diffraction structure analysis.     

Synthesis, antiviral and antifungal bioactivity of 2-cyano-acrylate derivatives containing phosphonyl moieties

Alkyl 2-cyano-3-methylthio-3-phosphonylacrylates were synthesized by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylates with dialkyl phosphites. The structures of the new compounds were characterized by elemental analyses, IR, 1H-, 13C- and 31P-NMR spectral data. These compounds were tested in vitro against pathogenic fungi, namely, Fusarium graminearum, Cytospora mandshurica and Fusarium oxysporum. Amongst all compounds, 2d and 2t were found to be effective against the tested fungi at 50 microg/mL. A half-leaf method was used to determine the in vivo protective, inactivation and curative efficacies of the title products against tobacco mosaic virus (TMV). Title compounds 2a and 2b were found to possess good in vivo curative, protection and inactivation effects against TMV with inhibitory rates at 500 mg/L of 60.0, 89.4 and 56.5 and 64.2, 84.2 and 61.2 %, respectively. To the best of our knowledge, this is the first report on the antiviral and antifungal activity of alkyl 2-cyano-3-methylthio-3-phosphonylacrylates.     

[BMIM]Cl Catalyzed One‐Pot Synthesis of α‐Aminophosphonate Derivatives Containing a 4‐Phenoxyquinazoline Moiety under Microwave Irradiation

[BMIM]Cl catalyzed three component Mannich‐type reaction of 4‐(quinazolin‐4‐yloxy)benzenamine and aldehyde with dialkyl phosphite under microwave irradiation has been described. The salient features of the reaction leading to new α‐aminophosphonates include shorter reaction time and good yields. The method is environmentally friendly and does not require toxic catalysts or solvents. To the best of our knowledge, this is the first report for [BMIM]Cl induced one‐pot synthesis of α‐aminophosphonate derivatives.     

Regioselective formylation of 1,3-disubstituted benzenes through in situ lithiation

A facile method of regioselective formylation of disubstituted benzene via in situ deprotonation/metalation using n-BuLi/TMEDA/DIPA has been developed. Effect of different electron withdrawing and electron donating substituents in 1,3-interrelated aromatic system was studied; the metalation mostly occurred at the 2-position to afford the desired products in high yields.