Gourhari Maiti

One-pot synthesis of dihydropyrimidinones catalysed by lithium bromide: an improved procedure for the Biginelli reaction

LiBr catalyses efficiently the three component condensation reaction of an aldehyde, a β-ketoester and urea in refluxing acetonitrile to afford the corresponding dihydropyrimidinones in high yield.

An efficient chemo and regioselective oxidative nuclear bromination of activated aromatic compounds using lithium bromide and ceric ammonium nitrate

Abstract A mild, efficient and highly chemo- and regioselective method for the bromination of electron rich aromatic molecules has been developed by electrophilic substitution of Br + , which was generated in situ from LiBr using ceric ammonium nitrate as the oxidant. Free aromatic amines remained unaffected under the reaction conditions.

Stereoselective synthesis of trisubstituted tetrahydrofurans by radical cyclisation reaction using a hypophosphite salt. Application to the total synthesis of (±)-dihydrosesamin

The stereoselective synthesis of tetrahydrofurans has been achieved from bromoalkynes and bromoalkenes by intramolecular radical cyclisation using a hypophosphite salt. This radical cyclisation strategy has successfully been applied to the total synthesis of a naturally occurring bioactive furanolignan, dihydrosesamin.

A mild and efficient method for oxidative halodecarboxylation of α,β-unsaturated aromatic acids using lithium bromide/chloride and ceric ammonium nitrate

Abstract A mild and efficient ecofriendly method for the halodecarboxylation of α,β-unsaturated aromatic acids has been developed by using lithium bromide/chloride and ceric ammonium nitrate in acetonitrile–water at room temperature to afford the vinyl halides in moderate to good yields.

Antimony Trichloride: An Efficient and Mild Catalyst for Cyclization of 2-Aminochalcones to the Corresponding 2-Aryl-2,3-Dihydroquinolin-4(1H)-ones

Antimony trichloride is an efficient catalyst for the cyclization of 2-amino chalcones to the corresponding 2-aryl-2,3-dihydroquinolin-4(1H)-ones under mild reaction conditions and in almost quantitative yields.

Antimony Trichloride–Catalyzed Michael Addition of Indoles to the α,β‐Unsaturated Ketones

Abstract Indoles undergo conjugate addition with α,β‐unsaturated ketones in the presence of a catalytic amount of antimony trichloride under refluxing condition to afford the corresponding Michael adduct in excellent yields. The substitution on the indole ring occurred exclusively at 3‐position without a trace of any N‐alkylated products.

Ceric ammonium nitrate as a convenient catalyst for protection of carbonyl compounds as 1,3-oxathianes

ABSTRACT A mild and efficient method for the protection of carbonyl compounds as 1,3-oxathianes has been established by the catalytic use of ceric ammonium nitrate at ambient temperature. While different types of aryl and alkyl ketones and aldehydes were protected smoothly, cyclic aryl ketones and diaryl ketones remained unaffected under the reaction conditions.

Impact of Structural Modification on the Photophysical Response of Benzoquinoline Fluorophores

Structural influence on the photophysical behavior of two pairs of molecular systems from the biologically potent benzoquinoline family, namely, dimethyl-3-(4-chlorophenyl)-3,4-dihydrobenzo[f]-quinoline-1,2-dicarboxylate, dimethyl-3-(2,6-dichlorophenyl)-3,4-dihydrobenzo[f]quinoline-1,2-dicarboxylate and their corresponding dehydrogenated analogues has been investigated exploiting experimental as well as computational techniques. The study unveils that dehydrogenation in the heterocyclic rings of the studied quinoline derivatives modifies their photophysics radically. Experimental observations imply that the photophysical behavior of the dihydro analogues is governed by the intramolecular charge transfer (ICT) process. However, the ICT process is restricted significantly by the dehydrogenation of the heterocyclic rings. Computational exertion leads to the proposition that the change in the electronic distribution in these molecular systems on dehydrogenation is the rationale behind the dramatic modification of their photophysics.

One-pot efficient pseudo-five-components synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) at room temperature assisted by K2CO3

ABSTRACT A convenient approach for the synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) by an efficient one-pot reaction of aromatic aldehydes, phenylhydrazine, and ethyl acetoacetate by using substoichiometric amount of K2CO3 in acetonitrile solvent at room temperature is described. This protocol of one-pot synthesis produced a library of bis-pyrazolylmethane derivatives, a potential bioactive compound in very good to excellent yields. GRAPHICAL ABSTRACT