Rina Mondal

Two expedient ‘one-pot’ methods for synthesis of β-aryl-β-mercaptoketones over anhydrous potassium carbonate or amberlyst-15 catalyst

AbstractTwo expedient one-pot methods have been developed for synthesis of β-aryl-β-mercaptoketones using acetophenones, benzaldehydes and thiols as starting materials. The methods involve microwave irradiation (5 min) of 1:1 mixtures of acetophenones and benzaldehydes over neutral alumina supported anhydrous potassium carbonate or amberlyst-15 in the first step, and that is followed by addition of thiol to the resulting material and keeping at room temperature for 1.5 h. Graphical AbstractAnhydrous potassium carbonate and amberlyst-15 are found to be efficient catalysts for the synthesis of β-aryl-β-mercaptoketones from acetophenones, benzaldehydes and thiols under solvent-free conditions. The experimental procedure is simple, involves shorter reaction times and results in good to excellent yield of the products.

Facile Condensation of Aromatic Aldehydes with Chroman-4-ones and 1-Thiochroman-4-ones Catalysed by Amberlyst-15 under Microwave Irradiation Condition

Different aromatic aldehydes and cinnamaldehyde undergo cross-aldol condensation with chroman-4-ones and1-thiochroman-4-ones in the presence of amberlyst-15 under microwave irradiation in solvent free condition to afford rapidly the corresponding E-3-arylidene and E-3-cinnamylidene derivatives, respectively, in high yield. This process is simple, efficient and environmentally benign.

Recent Applications of Potassium Carbonate in Organic Synthesis

Introduction ................................................................................. 393 I. Alkylation, Arylation and Acylation.............................................. 394 1. Alkylation Reactions.............................................................................394 a. O-Alkylation .....................................................................................394 b. N-Alkylation .....................................................................................396 c. S-Alkylation ......................................................................................401 d. C-Alkylation .....................................................................................402 2. Arylation Reactions ..............................................................................403 a. O-Arylation ......................................................................................403 b. N-Arylation ......................................................................................404 c. S–Arylation ......................................................................................405 d. C-Arylation ......................................................................................406 3. Acylation Reactions ..............................................................................406 II. Aldol Condensation and Related Reactions ................................... 408 III. Epoxide Opening .......................................................................... 410 IV. Michael Reaction .......................................................................... 410 1. C C Bond Formation ..........................................................................410 2. Aza-Michael.........................................................................................410 3. Oxa-Michael ........................................................................................411 4. Thia-Michael .......................................................................................411 V. Knoevenagel Reaction................................................................... 411 VI. Wittig Reaction............................................................................. 414 VII. Elimination Reactions ................................................................... 414 VIII. Hydration Reaction....................................................................... 415 IX. Cyclization Reactions.................................................................... 419 X. Multi-component Reactions .......................................................... 419 XI. Use as Acid Scavenger in Metal-catalyzed Cross-coupling Reactions ............................................................................... 419 XII. Miscellaneous Reactions................................................................ 424 Conclusion.................................................................................... 428

Synthesis of several types of 2,8-dioxabicyclo[3.3.1]nonanes using amberlyst-15 as an efficient recyclable heterogeneous catalyst

ABSTRACT A facile synthesis of 2,8-dioxabicyclo[3.3.1]nonane derivatives starting from simple molecules, such as 2-hydroxychalcones as one component and dimedone, 4-hydroxycoumarin, 2-hydroxynaphthoquinone, 2-naphthol or 1-naphthol, as the other has been achieved by use of amberlyst-15, a sulfonated polystyrene resin, as a recyclable heterogeneous catalyst. The methodology involves a domino sequence of Michael addition and two-stage cyclisation. GRAPHICAL ABSTRACT

A simple synthesis of E-9-aryl-5-arylidene-1-oxo-1,2,3,4,5,6,7, 8-octahydroxanthenes and their lower analogues from E,E-α,α′-diarylidenecycloalkanones

AbstractA simple and efficient synthesis of E-9-aryl-5-arylidene-1-oxo-1,2,3,4,5,6,7,8-octahydroxanthenes and their lower analogues has been developed by amberlyst–15 catalysed cyclocondensation of E,E-α,α′-diarylidenecyclohexanones and E,E-α,α′-diarylidenecyclopentanones, respectively, with cyclohexan-1,3-diones. The products were obtained in moderate to good yield and their structures were confirmed from analytical and spectral data. Graphical AbstractA simple and efficient synthesis of E-9-aryl-5-arylidene-1-oxo-1,2,3,4,5,6,7,8-octahydroxanthenes and their lower analogues has been developed by amberlyst-15 catalysed cyclocondensation of E,E-α,α′-diarylidenecyclohexanones and E,E-α,α′-diarylidenecyclopentanones, respectively, with cyclohexan-1,3-diones in anhydrous acetonitrile.

Simple Syntheses of Two New Benzo-Fused Macrocycles Incorporating Chalcone Moiety

Simple syntheses of the benzo-fused 26-membered macrocyclic bischalcone (19E,43E)-2.11.27.36-tetroxaheptacyclo[44.4.0.04,9.012,17.021,26.029,34.037,42]pentaconta-1(46),4(9),5,7,12(17),13,15,19,21,23,25,29,31,33,37,39,41,43,47,49-icosaene-18,45-dione (3) and the benzo-fused 13-membered macrocyclic chalcone (19E)-2.11-dioxatetracyclo[19.4.0.04,9.012,17]pentacosa-1(25),4(9),5,7,12(17),13,15,19,21,23-decaen-18-one (5) using very common starting materials and reagents are described. The compounds are new and they have been characterized from their analytical and spectral data.

An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

A rapid, efficient, and solvent-free methodology for synthesis of exocyclic α,β-unsaturated ketones of the categories E-3-arylidene-4-chromanones, E-2-arylidene-1-tetralones, E-2-arylidene-1-indanones, E-3-cinnamylidene-4-chromanones, E-2-cinnamylidene-1-tetralones, E-2-cinnamylidene-1-indanones, α,α′-(E,E)-bis(arylidene)-cycloalkanones, and α,α′-(E,E)-bis(cinnamylidene)-cycloalkanones has been developed through cross-aldol condensation of the constituent cyclic ketones and aldehydes by microwave irradiation over anhydrous potassium carbonate. However, for condensation of 1-thio-4-chromanones with aromatic aldehydes by this method, the initially formed exocyclic α,β-unsaturated ketone has been found to undergo isomerization yielding 3-(arylmethyl)thiochromones.

On the regioselectivity of the amberlyst-15 catalyzed condensation of 2-hydroxychalcones and 4,4-dimethylcyclohexane-1,3-dione

Abstract Amberlyst-15 catalyzed condensation of 2-hydroxychalcones and 4,4-dimethylcyclohexane-1,3-dione in refluxing toluene was found to show regioselectivity resulting in (6R*,12S*)-2,2-dimethyl-6-phenyl-2,3,4,12-tetrahydro-1H-6,12-methanodibenzo[d,g][1,3]dioxocin-1-ones as the major product.Graphical abstract

3-[4-Bromo-α(R*)-methoxybenzyl]-6-chloro-3(S*),4(S*)-dihydroxychroman: X-ray and DFT Studies

Sodium borohydride reduction of E-3-benzylidenechromanone epoxides in dry methanol has afforded 3(S*), 4(S*)-dihydroxy-3-[α(R*)-methoxybenzyl]chromans as an interesting class of products, the structures of which have been assigned mainly from spectral data and consideration of the mechanistic aspects. X-ray diffraction study of one of them, 3-[4-bromo-α(R*)-methoxybenzyl]-6-chloro-3(S*),4(S*)- dihydroxychroman, is performed. The title compound crystallizes in the monoclinic sp. gr. P21/n, with a = 13.336(6) Å, b = 10.866(5) Å, c = 27.166(11) Å, β = 95.193(6)°, V = 3920(3) Å3, and Z = 8. Supramolecular construction of the compound involves O–H···O intermolecular hydrogen bonds as well as three other types of non-covalent interactions which are responsible for crystal packing. Density functional theory was applied for geometry optimization, molecular orbital calculations, and prediction of UV spectral features. The geometric parameters (bond lengths, bond angles, and dihedral angles) for the representative compound obtained from density functional theory with B3LY6-31G basis set were in good agreement with experimental values.

Crystal Structures of Two Macrocyclic Bischalcones Possessing 26-Membered Rings

Single crystal X-ray diffraction of two macrocyclic bischalcones, namely, (2E,25E)-11,17,33,37-tetraoxapentacyclo[36.4.0.05,10.018,23.027,32]dotetraconta-1(42),2,5,7,9,18,20,22,25,27,29,31,38,40-tetradecaene-4,24-dione(1) and (2E,24E)-11,16,32,37-tetraoxapentacyclo[36.4.0.05,10.017,22.026,31]dotetraconta-1(42),2,5,7,9,17,19,21,24,26,28,30,38,40-tetradecaene-4,23-dione(2), each containing a 26-membered ring, has been studied. Compound 1 belongs to the monoclinic system, space group C2/c with a = 34.3615(9) A, b = 12.7995(3) A, c = 14.6231(3) A, β = 96.912(2)°,  V = 6,384.6(3) A3, and Z = 8. Compound 2 is triclinic, space group P-1 with a = 10.066(2) A, b = 10.670(3) A, c = 16.590(3) A, α = 85.95(2), β = 89.244(14), γ = 62.211(13), V = 1572.0(6) A3, and Z = 2. Intermolecular C–H⋯O hydrogen bonding interactions are present in both compounds.