A facile and efficient synthesis of highly functionalised 3,3′-dispiropyrrolidine- and 3,3′-dispiropyrrolizidine bisoxindoles via [3+2] cycloaddition

A highly efficient and general method for the preparation of (Z)-allylic bromides derived from Morita-Baylis-Hillman adducts

“…Allylic bromides 1 are versatile building blocks of many important substances including natural products, heterocycles and biologically-active molecules [1][2][3][4][5][6][7][8][9][10][11][12][13] (Scheme 1). These multifunctional compounds can be prepared from α-methylene-β-hydroxyesters 2, which are easily obtained by the well-recognized Morita-BaylisHillman reaction.…”

“…18 In spite of the fairly good yields often achieved for this transformation, the required use of large quantities of noxious hydrobromic acid is a major disadvantage due to safety and environmental concerns. Alternative methods for converting alcohol 2 to bromide 1 include the use of NBS/Me 2 20 and also bromine salts immobilized in ionic liquids 21 or in the presence of solid catalysts such as montmorillonite KSF clay, 22 Amberlyst-15, 23 silica gel-supported NaHSO 4 , 24 and silica gel alone under microwave irradiation. 25 Although all the above procedures have their own applications, many of them suffer from one or more drawbacks such as the use of harmful conditions, high temperatures, special equipment or commercially unavailable reagents or catalysts, eventually leading to long reaction times or low yields.…”

Catalyst-free alkylation of aminopyrazole by isatin in water

“…Oxindole derivatives have long been the focus of considerable attention due to their abundance in numerous natural products as well as their extensive applications in biology and pharmacology [1][2][3][4][5]. A great number of compounds bearing oxindole moieties are reported to possess significant antibacterial, antiprotozoal, antiinflammatory and antitumor properties [6,7], and they have been widely employed as potential synthons for the synthesis of alkaloids, drug candidates and clinical pharmaceuticals [8][9][10].…”

Ultrasound-assisted, ZnBr2-catalyzed regio- and stereoselective synthesis of novel 3,3′-dispiropyrrolidine bisoxindole derivatives via 1,3-dipolar cycloaddition reaction of an azomethine ylide

“…General procedure for synthesis of the 3,3′-dispiropyrrolidine bisoxindole (8a-l). A mixture of (E)-3-benzylideneindolin-2-one 7a-l (1 mmol), isatin (147 mg, 1 mmol), sarcosine (89 mg, 1 mmol) and anhydrous ZnBr2 (20%, 45 mg, 0.2 mmol) in methanol (10 mL) was sonicated for 30 minute at room temperature (25)(26)(27)(28)(29)(30) o C). After completion of the reaction as monitored by TLC, the mixture was poured in ice cold water and the precipitates were filtered and air dried.…”

“…The challenges associated with the synthesis of spiro-or dispiro-heterocycles containing the 3,3′-pyrrolidinyl-spirooxindole core have made them the subject of several elegant synthetic investigations. [22][23][24][25][26][27][28][29][30][31][32] Ultrasound irradiation has increasingly been used as a powerful tool for the preparation of organic molecules either in homogeneous or in heterogeneous liquid reaction systems. 33,34 The success and advantages of this method include shorter reaction time, higher yield, higher product purity, improved selectivity, reduced side product formation, and use of milder reaction conditions when compared with conventional heating.…”