Base Catalyzed Abnormal [3 + 2]-Cycloaddition between Isatin N,N′-Cyclic Azomethine Imine 1,3-Dipole and 3-Methyleneoxindole for the One-Step Construction of Tetracyclic Bispirooxindoles

Abstract

An abnormal [3 + 2]-cycloaddition and highly effective and convenient one-step preparation of tetracyclic bispirooxindoles containing two all-carbon quaternary spirocenters from isatin N,N′-cyclic azomethine imine 1,3-dipole and 3-methyleneoxindole in the presence of catalytic organic base has been disclosed. A variety of bispirooxindoles bearing a dinitrogen heterocycle with four adjacent cycles have been obtained in excellent yields (up to 95%) and diastereoselectivities (>99:1) under mild conditions.

Spiro Scaffold Chiral Organocatalyst of 3,2′-Pyrrolidinyl Spiro-oxindole Amine and Its Catalytic Evaluation in the Enantioselective Aldol Condensation between 3-(3-Hydroxy-1H-pyrazol-1-yl)-Oxindole and Paraformaldehyde

“…As we have rationalized, this new l -prolineamide like spiro chiral second amine may be both a new kind of potential organocatalyst and pharmaceutical candidate. On the basis of our studies on organocatalysis and our recent works on the new synthon of isatin N , N ′-cyclic azomethine imine 1,3-dipole 6 invented and prepared by us in 2017, we found 1,3-dipole 6 could be transformed to a new and unique synthon of 3-(3-oxo-2,3-dihydro-1 H -pyrazol-1-yl)-oxindole 7 under basic conditions, which can react with paraformaldehyde in a catalytic weak base. Herein, we wish to evaluate the spirocyclic catalysts of 1 , 2 , and 5 in the enantioselective aldol condensation between synthon 7 and paraformaldehyde, which is generally regarded as an active electrophile (Scheme ).…”

An ultrasound assisted synthesis of spirooxindolo-1,2,4-oxadiazoles via [3+2] cycloaddition reaction and their anti-cancer activity

“…The [3+2] cycloaddition process is a highly regio-selective approach for the synthesis of spiroxindoles. 12,13,14,15 Spirooxindole alkaloids found in nature, such as horsfiline, extracted from Horsfieldia superba are used in traditional medicine (Figure 1). 16,17 However, the spiroxindoles having 1,2,4-oxadiazole ring systems are rare in the literature.…”

K2CO3-Promoted Formal [3+3]-Cycloaddition of N-Unsubstituted Isatin N,N′-Cyclic Azomethine Imine 1,3-Dipoles with Knoevenagel Adducts

“…To date, the reactions of isatin N , N ′-cyclic azomethine imines have rarely been studied and demonstrated by a few examples [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. So, it is urgent to explore the new 1,3-dipolar cycloaddition of isatin N , N ′-cyclic azomethine imines.…”