Organocatalytic Asymmetric Mannich Reaction of 3-Hydroxyoxindoles/3-Aminooxindoles with in Situ Generated <i>N</i>-Boc-Protected Aldimines for the Synthesis of Vicinal Oxindole–Diamines/Amino Alcohols
A highly efficient asymmetricMannichreaction of 3-monosubstituted 3-aminooxindoles/3-hydroxyoxindoles with in situ generated N-Boc-protected aldimines catalyzed by the chiral bifunctional thiourea–tertiary amine catalyst has been developed. Under mild reaction conditions, a series of structurally diverse vicinal oxindole–diamines/amino alcohols were smoothly obtained in moderate to high yields (up
copper-catalyzed intramolecular C(sp2)–N cross-coupling reaction of 3-aminooxindoles with 2-bromobenzyl bromides, a wide range of 2,3′-spirobi[indolin]-2-ones were smoothly obtained in moderate to good yields. A plausible catalytic cycle for this tandem reaction process was proposed based on the control experiments. This study represents a new perspective for the synthesis of structurally diverse spirocyclic oxindoles
Tandem Michael Addition–Ring Transformation Reactions of 3-Hydroxyoxindoles/3-Aminooxindoles with Olefinic Azlactones: Direct Access to Structurally Diverse Spirocyclic Oxindoles
An efficient method for the direct construction of two classes of spirocyclic oxindoles by the reactions of 3-hydroxyoxindoles/3-aminooxindoles and (Z)-olefinic azlactones through a tandem Michael addition-ring transformation process has been developed. With DBU as the catalyst, a range of spiro-butyrolactoneoxindoles and spiro-butyrolactamoxindoles, containing an oxygen or a nitrogen heteroatom, respectively, in the spiro stereocenter, were smoothly obtained with good to excellent diastereoselectivities in high yields.