Rajashri Salunkhe

Ligand-free Pd catalyzed cross-coupling reactions in an aqueous hydrotropic medium

A simple, efficient and ligand-free protocol for the Suzuki–Miyaura reaction and base-free Heck–Matsuda reactions under mild reaction conditions have been developed over palladium supported on activated carbon (Pd/C) in an aqueous hydrotropic solution. The catalyst Pd/C was fully characterized by TG-DTA, SEM, EDS, XRD, XPS, BET and ICP-AES analyses. This green methodology represents a cost-effective and operationally convenient method for the synthesis of a variety of biaryls, prochiral ketones, and acrylates under the conditions that are tolerant for a broad range of functional groups with good to excellent yields. The developed Pd/C–aqueous hydrotrope combined catalytic system is well suited for the 3R approach (reducible, robust, and recyclable) for different cross-coupling reactions without an appreciable loss of its activity.

Synergistic catalysis by an aerogel supported ionic liquid phase (ASILP) in the synthesis of 1,5-benzodiazepines

An ionic liquid film of [Bmim]Cl containing an organometallic catalyst (Cp2ZrCl2) has been anchored on the porous matrix of an aerogel by adsorption interactions. The synthesized aerogel supported ionic liquid phase catalyst was successfully employed in the synthesis of medicinally relevant 1,5-benzodiazepines.

Ultrasound promoted efficient and green synthesis of β-amino carbonyl compounds in aqueous hydrotropic medium.

Ultrasound promoted synthesis of β-amino carbonyl compounds in aqueous hydrotropic medium at ambient temperature is reported. The remarkable features of the new procedure are shorter reaction time, excellent yields in aqueous medium, cleaner reaction profile and simple experimental and work-up procedure.

A Merrifield resin supported Pd–NHC complex with a spacer(Pd–NHC@SP–PS) for the Sonogashira coupling reaction under copper- and solvent-free conditions

Synthetic applications of a polymer supported air-stable palladium NHC complex with a spacer (catalyst 6, Pd–NHC@SP–PS) and without a spacer (catalyst 7, Pd–NHC@PS) have been studied for the Sonogashira cross-coupling reaction. The catalysts were prepared by immobilizing pre-formed IL on the polymer and reacting the resultant modified polymer with Pd(OAc)2 in THF at 60 °C. Both the catalysts were characterized using IR, SEM, EDS, ICP, XPS and TGA/DTA. Catalyst 6 has been found to be more active than catalyst 7, due to the greater accessibility of active catalytic sites, for a variety of aryl bromides and terminal alkynes in solvent and copper free Sonogashira cross-coupling reactions under aerobic conditions. The effect of the spacer, nature of base, reaction temperature, the catalyst loading as well as reusability was also investigated.

Silica Tethered Pd–DABCO Complex: An Efficient and Reusable Catalyst for Suzuki–Miyaura Reaction

A palladium-based catalyst supported on DABCO-functionalized silica was successfully prepared by a facile procedure. The prepared heterogeneous catalyst showed a high activity for the Suzuki–Miyaura reaction of aryl bromides, affording excellent yield in all the cases investigated. Interestingly, the catalyst could be quantitatively recovered from the reaction mixture and recycled for five times without any significant loss in activity. Furthermore, this protocol could be extended to the palladium catalyzed synthesis of annulated pyrazines.Graphical Abstract

Remarkable anti-breast cancer activity of ferrocene tagged multi-functionalized 1,4-dihydropyrimidines.

A novel series of ferrocene tagged multi-functionalized 1,4-dihydropyrimidines is synthesized by base catalyzed cyclocondensation between ferrocenyl chalcones and amidines. The structures of synthesized compounds were established on the basis of (1)H NMR, (13)C NMR, FTIR spectroscopy as well as by mass spectrometry. The compounds were evaluated for in vitro anticancer activity. The most active compounds from the series displayed GI50 value equal to doxorubicin against the strain of human breast cancer cell line MDA-MB-435.

Hydrotrope Induced Catalysis in Water: A Clean and Green Approach for the Synthesis of Medicinally Relevant Bis(indolyl)methanes and 2-Aryl Benzimidazoles

Abstract An efficient synthesis of medicinally relevant bis(indolyl)methanes and 2-aryl benzimidazoles has been achieved in an aqueous hydrotropic solution at ambient temperature. Substantial enhancements in the rates of the reactions along with easy recovery of the products were noted. Additionally, the aqueous hydrotropic solution could be reused for several cycles with modest change in yields of products. GRAPHICAL ABSTRACT

An expedient synthesis of oxazolones using a cellulose supported ionic liquid phase catalyst

A novel cellulose supported ionic liquid phase catalyst containing hydroxide ions ([CellFemImi]OH) has been synthesized by covalent anchoring of 1-N-ferrocenylmethyl imidazole in the functionalized cellulose matrix followed by an anion metathesis reaction. The [CellFemImi]OH was characterized by various techniques including FT-IR, FT-Raman, 13C solid state NMR, X-ray diffraction, energy dispersive X-ray (EDX) analysis, field emission scanning electron microscopy (FESEM) and thermogravimetric analysis. The [CellFemImi]OH was effectively employed as a heterogeneous catalyst in the synthesis of oxazolones by cyclocondensation of aryl aldehydes with hippuric acid in the presence of acetic anhydride.

Aqueous hydrotrope: an efficient and reusable medium for a green one-pot, diversity-oriented synthesis of quinazolinone derivatives

A library of quinazolinones was prepared by the one-pot three-component reaction of isatoic anhydride, ammonium salts/amines, and various electrophiles using aqueous hydrotropic solution as an efficient, economical, reusable, and green medium giving good to excellent yields of products in very short time. The method offers a versatile way for the development of diversity-oriented synthesis of quinazolinones.

Aqueous extract of Balanites roxburghii fruit: a green dispersant for C–C bond formation

An aqueous biosurfactant solution, a biobased green acidic catalyst for Knoevenagel condensation of 1,3-indanedione with aryl aldehydes and tandem Knoevenagel–Michael reaction of 3-methyl-1-phenylpyrazole with aryl aldehydes, has been reported for the first time. The synthetic pathway complies with several key requirements of green chemistry principles such as the use of renewable feedstock, aqueous conditions, waste prevention, atom economy along with the biodegradable and recyclable catalyst. Thus the presented protocol offers an attractive option because of its versatility, ecological safety, environmental acceptance and sustainability.