Diastereoselective tandem oxidation/Michael/aldol reaction: unprecedented formation of dispirocyclopentanebisoxindoles and dispiro[acenaphthylene-1,1'-cyclopentane-3',1''-acenaphthylene]-2,2''diones

Regio- and diastereoselective synthesis of thioxothiazolidin-indolin-2-ones, oxoindolin-carbamodithioate hybrids, and their base-catalyzed conversion into dispirocyclopentanebisoxindoles

In this publication, we reported a regio-, diastereoselective, and kinetically controlled reaction for synthesizing thioxothiazolidin-indolin-2-ones, oxoindolin-carbamodithioate hybrids, and their base-catalyzed conversion into dispirocyclopentanebisoxindoles. Obtaining only the kinetic thioxothiazolidin-indolin-2-one products together with their straightforward conversion to dispirocyclopentanebisoxindoles, excellent regio- and diastereoselectivity, easy reaction workup, and one-pot synthetic operation are considerable advantages of this work.

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

An efficient tosylhydrazine-mediated conjugate reduction of 3-phenacylideneoxindole and sequential Michael/intramolecular aldol reaction is reported under base-catalyzed conditions towards the formation of densely substituted dispirocyclopentanebisoxindole derivatives. The reaction proceeded in a diastereoselective manner to afford four chiral stereocenters. The method also has advantages of wide substrate scope, readily available starting materials and operational simplicity through one pot reaction.

Tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles: construction of vicinal quaternary carbon centers

A novel tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles has been developed, providing dispirooxindole–cyclopentane–cyclohexadienones with vicinal quaternary carbon centers.

Divergent Michael/Aldol Cascades Under Semi-Aqueous Conditions: Synthesis of Cyclopenta- and Cycloheptannulated (Hetero)arenes

The synthesis of 3-acetoxyindanones and (hetero)arene-fused dihydrotropones was achieved via divergent annulation cascades. Under mild aqueous and basic conditions, α-substituted enone-aldehydes and 1,3-carbonyls undergo a Michael/aldol/hemiketalization/retro-aldol cascade for the formation of 3-acetoxyindanones possessing two contiguous stereogenic centers, one of which is an all-carbon quaternary center. On the other hand, the same enone-aldehydes generate new classes of fused-dihydrotropones upon reaction with 2,4-dioxobutanoates under merely the same reaction conditions via a Michael/aldol/lactonization/decarboxylation cascade.

DBU-catalyzed [3 + 2] cycloaddition and Michael addition reactions of 3-benzylidene succinimides with 3-ylidene oxindoles and chalcones

A metal-free DBU catalyzed protocol has been developed for the regioselective [3 + 2] cycloaddition reactions of 3-benzylidene succinimides with 3-ylidene oxindoles to furnish spirooxindole derivatives. The 3-benzylidene succinimides underwent Michael addition with chalcones to provide benzylidene succinimide-tethered propanones. All the reactions proceeded under mild conditions and the products were isolated by simple filtration and washing with ethanol in good yields. The current methodology utilizes simple precursors and provides functionally-rich succinimides with two to five contiguous stereocenters in excellent diastereoselectivity and with complete regioselectivity.