DABCO-promoted highly diastereo- and regioselective construction of C-3 functionalized spirooxindoles via [3 + 2] cycloaddition of 2-aryl/heteroarylidene-1H-indene-1,3(2H)-diones with N-2,2,2-trifluoroethylisatin ketimines at ambient conditions

DBU-catalyzed diastereoselective 1,3-dipolar [3+2] cycloaddition of trifluoroethyl amine-derived isatin ketimines with chalcones: synthesis of 5'-CF3-substituted 3,2'-pyrrolidinyl spirooxindoles

A diastereoselective 1,3-dipolar cycloaddition reaction between trifluoroethyl amine-derived isatin ketimines and chalcones was successfully achieved in the presence of DBU. A series of 5'-CF3-substituted 3,2'-pyrrolidinyl spirooxindoles were efficiently synthesized with high yields and excellent diastereoselectivities (up to 89% yield, and >99 : 1 dr). The in vitro anticancer activities of these highly functionalized spiro[pyrrolidin-3,2'-oxindole] derivatives were evaluated.

Enantioselective Synthesis of Octahydrofuranoindole Core of Aspidosperma Alkaloids via a Diels-Alder/Reduction/Fluoroetherification Reaction Sequence

Herein, we disclose the enantioselective synthesis of novel tricyclic fluorooctahydrofuranoindole spirooxindoles bearing five contiguous stereocenters via an organocatalytic sequential Diels-Alder/Reduction/Fluoroetherifiction reaction strategy. The potential of the developed approach was witnessed by generating vast examples (up to 20 examples) of library molecules embedding natural product core with good yields and phenomenal diastereo- and enantioselectivities (up to 77 % overall yield, up to 99 % ee and 10 : 1 dr). The synthetic utility of our protocol was further demonstrated by synthesizing tricyclic iodooctahydroindole spirooxindole framework through sequential Diels-Alder/reduction/iodoetherification reaction in 65 % overall yield and excellent stereoselectivity (99 % ee and 4 : 1 dr).

Stereoselective synthesis of CF3-containing spirocyclic-oxindoles using N-2,2,2-trifluoroethylisatin ketimines: an update

The introduction of fluorine-containing groups into organic molecules either changes or improves the characteristics of the target compounds. On the other hand, spirocyclic-oxindoles featuring C-3 functionalized sp3-hybridized carbon atoms of three-dimensional orthogonally shaped molecules were well recognized in the core structure of varied natural products and synthetic pharmaceutical targets. Consequently, the construction of spirooxindoles by an elegant synthetic approach with efficient stereocontrol has received tremendous interest over the past decades. In this context of the synergic combination of the features associated with fluorine-containing compounds and the synthetic and medicinal efficiency associated with spirooxindoles, the stereodivergent installation of CF3 groups embedded with spirooxindoles is of increasing academic and scientific interest. This mini-review article is dedicated to demonstrating a critical overview of the recent stereoselective synthesis of spirocyclic-oxindoles featuring trifluoromethyl groups by employing the reactivity of N-2,2,2-trifluoroethylisatin ketimines as an efficient and easily prepared synthon, and covers the literature reports from 2020 to date. Besides exploring the advancements accomplished in this area, we also investigate the limitations associated with reaction discovery, mechanistic rationalization, and future applications.