Electrophilic Amide Allylation of 3-Heterosubstituted Oxindoles: A Route to Spirocyclic 2-Oxindoles Containing the α-Methylene-γ-butyrolactam Structure
spirocyclic 2‐oxindoles containing the α‐methylene‐γ‐butyrolactam structure via “electrophilic amide allylation” is reported. The key reaction was accomplished by using acetoxy methacrylamides and tetrakis(triphenylphosphine)palladium as catalyst, affording a variety of the amide allylated products in excellent yields.
Chiral Lewis bases facilitated the synthesis of highly functionalized spirooxindoles containing α-exo-methylene-γ-butyrolactones in high yields (76–92 %) and excellent enantioselectivities (up to 98 % ee) at ambient temperature.
alkylation of 3-hydroxy-oxindole derivatives is achieved. The reaction starts from addition of 4-dimethylaminopyridine (DMAP)-boryl radical to the amide carbonyl oxygen atom, which induces a spin-center shift process to promote the C–O bond cleavage. The elimination of a hydroxide anion from a free hydroxy group is also accomplished. Capture of the generated carbon radical with alkenes furnishes a variety
synthesized in very good enantio- (up to 97% ee) and diastereoselectivities (dr up to 7.6:1) with contiguous quaternary and tertiary stereogenic centers by employing tartrate derived bi(oxazoline) in Pd-catalyzed allylation of 3-OBoc-oxindole. Synthetic utility of 3-allyl-3-hydroxyoxindole was demonstrated by synthesizing a highly substituted spiro(oxindole-3,2′-tetrahydrofuran) derivative in good yield and