A.R. Prasad

Iodine as novel reagent for the 1,2-addition of trimethylsilyl cyanide to ketones including α,β-unsaturated ketones

Molecular iodine is found to catalyze efficiently the addition of trimethylsilyl cyanide to a range of simple and functionalized ketones under very mild and convenient conditions to afford the corresponding cyanohydrin trimethylsilyl ethers in excellent yields in a short reaction period with high selectivity. α,β-Unsaturated ketones selectively afford the corresponding 1,2-adducts without the formation of 1,4-adducts under similar reaction conditions.

Glaser oxidative coupling in ionic liquids: an improved synthesis of conjugated 1,3-diynes

Terminal alkynes undergo oxidative-coupling smoothly in the presence of the CuCl-TMEDA catalytic system in hydrophobic [bmim]PF6 ionic liquid under aerobic conditions to produce 1,3-diynes in excellent yields under mild conditions. The substrates, alkynes, show enhanced reactivity and selectivity in ionic liquids (ILs). The recovery of the catalyst is facilitated by the hydrophobic nature of the [bmim]PF6 ionic liquid.

Ultrasound-accelerated synthesis of 3,4-dihydropyrimidin-2(1H)-ones with ceric ammonium nitrate

Ceric ammonium nitrate efficiently catalyzes the three component condensation of an aldehyde, β-ketoester and urea in methanol to afford the corresponding dihydropyrimidinones in excellent yields under sonication. Other oxidants such as manganese triacetate and Oxone were also found to catalyze this transformation under similar conditions.

Room temperature ionic liquids promoted three-component coupling reactions: a facile synthesis of cis-isoquinolonic acids

Room temperature ionic liquids are found to catalyze efficiently the three component-coupling reactions of aldehydes, amines and homophthalic anhydride under mild and convenient conditions to afford the corresponding cis-isoquinolonic acids in excellent yields with high cis-selectivity.

Electroantennogram responses of Apanteles obliquae (Hym., Braconidae) to various infochemicals

Abstract:  The electroantennogram recording technique (EAG) was used to study the olfactory sensitivity of Apanteles obliquae (Hym., Braconidae), a gregarious larval endoparasitoid of Spilosoma obliqua (Walker) (Lep., Arctiidae), to 25 general plant volatiles belonging to alcohol, aldehyde and terpenoid groups and also to volatiles from the host and plant–host complex. The EAG data indicated different olfactory sensitivity between the sexes, not only to individual plant volatiles but also to the volatiles from host and plant–host complex. Females were found to be more responsive than males. However the synthetic sex pheromone blend of the host insect elicited similar EAG responses in both sexes. The EAG data of the present study is correlated with the reported behaviour observed in other parasitoids.

Total synthesis of enantiomers of (3Z,6Z)-cis-9,10-epoxy 1,3,6-henicosatriene — the pheromonal component of Diacrisia obliqua

Synthesis of enantiomers of (3Z,6Z)-cis-9,10-epoxy 1,3,6-henicosatriene, the pheromonal component of Diacrisia obliqua was achieved through alkylative epoxide rearrangement and stereoselective Wittig olefination reactions as the key steps.

[Bmim]PF6/RuCl3·xH2O: a novel and recyclable catalytic system for the oxidative coupling of β-naphthols

2-Naphthols readily undergo oxidative coupling in the presence of RuCl3·xH2O in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) ionic liquid under aerobic conditions to afford binaphthols in excellent yields with high selectivity. The β-naphthols show enhanced reactivity in ionic liquids, thereby reducing reaction times and improving the yields significantly. The recovered ionic liquid containing ruthenium catalyst can be reused in three to four successive runs with a gradual decrease in activity.

Isolation, identification, synthesis, and bioefficacy of female Diacrisia obliqua (Arctiidae) sex pheromone blend. An Indian agricultural pest

Diacrisia obliqua is a polyphagous pest especially on oil seed crops. Adult female sex pheromone blend consists of five pheromone components, which include (3Z,6Z)-cis-9,10-epoxyl,3,6-henicosatriene and (3Z,6Z)-cis-9,10-epoxy3,6-henicosadiene. Synthesis of these enantiomers was achieved through alkylative epoxide rearrangement and stereoselective Wittig olefination reactions as key steps. Bioefficacy experiments both at laboratory and minifield were very positive.

Stereoselective Formal Synthesis of (-)-Salicylihalamides A and B Via Prins Cyclisation

A stereoselective and convergent formal approach to Salicylihalamide A and B is achieved through our recently developed strategy for the construction of polyketide precursors via Prins cyclisation. The approach mainly relies upon reductive opening of 1-iodomethyl cyclic ethers, Mitsunobu inversion and ring closing metathesis along with Prins cyclisation.

Electrophysiological and behavioural responses of groundnut seed beetle Caryedon serratus (Olivier) (Coleoptera: Chrysomelidae) to conspecific and groundnut seed chemical cues

The olfactory and behavioural responses of groundnut seed-beetle, Caryedon serratus Olivier to semiochemicals isolated from conspecific insects as well as from groundnut seed headspace volatiles were investigated by coupled Gas Chromatography-Electroantennogram (GC-EAD) and Y-tube olfactometer bioassays. Significant orientation responses of male bruchids to the headspace volatiles from females and orientation responses of both sexes of seed beetles to headspace volatiles from male extracts confirm the existence of both sex and aggregation pheromone systems in C. serratus. Coupled GC-EAD analyses of headspace volatiles of female extract revealed seven bioactive peaks with strongest antennal responses of males towards flame ionization (FID) peaks at retention times of 3 min and 26 min, respectively. GC-EAD profiles of male headspace volatile extract indicated the presence of three distinct bioactive peaks elicited by both male and female antennae. These findings provided necessary leads for the identification of compounds in order to develop environmentally safe semiochemical-based control method for C. serratus.