Pd-Catalyzed Asymmetric Annulative Dearomatization of Phenols for Regio- and Enantioselective Synthesis of Spirocyclohexadienones

Iridium/Acid-Dual Catalyzed Enantioselective Intramolecular Allylic Dearomatization Reaction of Allylic Alcohol Tethered α- and β-Naphthols

The first catalytic enantioselective intramolecular allylic dearomatization of allylic alcohol tethered α- and β-naphthols has been developed with iridium/acid-dual catalysis. A wide range of polycyclic spiroketones containing vicinal tertiary and quaternary carbon stereocenters were readily prepared in good to high yields with high diastereo- and moderate to excellent enantioselectivities. An unusual anti-Markovnikov Wacker oxidation has also been shown in synthetic transformations.

Organocatalytic Asymmetric Dearomative Spirocyclization/Oxa-Michael Addition Sequence: Synthesis of Polycyclic Tetralones

Herein, an organocatalytic asymmetric dearomative spirocyclization/oxa-Michael addition sequence with a newly designed substrate having two naphthol motifs has been developed. The reaction proceeds through in situ chiral vinylidene ortho-quinone methide (VQM) intermediate formation, dearomative spirocyclization of naphthol, and an oxa-Michael addition reaction. The densely functionalized tetralone products were formed in high yields with high diastereo- and enantioselectivities.

Synthesis of 1,7-Fused Indolines Tethered with Spiroindolinone Based on C-H Activation Strategy with Air as a Sustainable Oxidant

Herein, we present an efficient synthesis of 1,7-fused indolines tethered with a spiroindolinonyl moiety through the cascade reaction of indolin-1-yl(aryl)methanimines with diazo oxindoles. To the best of our knowledge, this is the first example in which 1,7-fused indoline skeleton was constructed along with the simultaneous introduction of a spiro element initiated by the C-H bond activation of indoline. In forming the title product, the indoline substrate and the diazo coupling partner demonstrated an unprecedented reaction pattern in which the latter acts as a C1 synthon to participate in the construction of the spirocyclic scaffold through the reductive elimination of a key seven-membered Ru(II) species by using air as an effective and sustainable oxidant to regenerate the active catalyst. Moreover, studies on the cytotoxicity of selected products against several human cancer cell lines demonstrated their potential as lead compounds for the development of anticancer drugs. With notable features such as simple and economical substrates, pharmaceutically valuable products with sophisticated spirocyclic skeleton, mild reaction conditions, cost-free and sustainable oxidants, high efficiency, excellent compatibility with diverse functional groups, and scalability, this method is expected to find wide applications in related areas.