The regio- and stereoselective ring-opening of spiro-epoxyoxindoles with ammonia has been reported for the construction of 3-hydroxy-3-aminomethyloxindoles in high yields (up to 90%) and enantioselectivities (up to 99% ee) under mild and catalyst-free conditions. The reaction could be scaled up to the gram-scale and be used in the synthesis of analogues of dioxibrassinin and spirobrassinin.

AbstractAn efficient process involving the catalytic kinetic resolution of racemic spiro-epoxyoxindoles with the simultaneous enantioselective Friedel–Crafts alkylation of indoles has been realized using a chiral phosphoric acid catalyst. The reaction provides two useful intermediates in high yields and excellent enantioselectivities. Performing the catalysis on a gram scale led to (R)-3-(3-indolyl)-oxindole-3-methanol, which was used in the asymmetric formal total synthesis of (+)-gliocladin C. Notably, the enantiomers (S)-3-(3-indolyl)-oxindole-3-methanol can be obtained easily by the reaction of the resolved spiro-epoxyoxindole with indole.

The C1-substituted tetrahydroisoquinolines and 1,2-dihydroisoquinoline constitute an important group and are interesting structural motifs found in many natural products and pharmaceuticals. In this context, a phosphoric-acid-catalyzed enantioselective dearomative arylation of isoquinolines was realized, providing the chiral dihydroisoquinolines with indole substituents at the C1-position in good results (up to >99% yield and 97% ee). The reaction features mild reaction conditions and operational simplicity, which make it an attractive approach to the discovery of biologically interesting α-indolisoquinolines.Keywords: chiral phosphoric acid; dearomative arylation; enantioselective; indole; isoquinolines

A catalyst-controlled switch of regioselectivity in asymmetric allylic alkylation of oxazolones with MBHCs was described. The SN2′–SN2′ reaction catalysed by a quinine-derived base produced γ-selective secondary allylic oxazolone derivatives, whereas the addition–elimination reaction catalysed by an amino acid-derived bifunctional urea catalyst provided β-selective primary adducts.

The first chiral phosphoric acid catalyzed highly diastereo- and enantioselective 1,3-dipolar cycloaddition reaction of azlactones and methyleneindolinones was disclosed. By using a BINOL-derived chiral phosphoric acid as the catalyst, azlactones were activated as chiral anti N-protonated 1,3-dipoles to react with methyleneindolinones to yield biologically important 3,3′-pyrrolidonyl spirooxindole scaffolds in high yields, with good-to-excellent diastereo- and enantioselectivity.

A highly enantioselective oxidative dearomatization of naphthols with quinones catalyzed by a chiral spirocyclic phosphoric acid is described. The strategy provides concise access to enantioenriched cyclohexadienones with a quinone moiety. Remarkably, the obtained products could be easily transformed to a potentially useful dihydronaphtho[2,1-b]benzofuran scaffold.

This review summarizes the recent advances in the field of asymmetric dearomatization of phenols and their applications in the total synthesis of some complex natural products. The dearomatization discussed here includes metal catalysed direct dearomatization, organocatalytic dearomatization and hypervalent iodine mediated dearomatization.

The copper-catalyzed cascade azidation–cyclization of tryptophols and tryptamines has been developed. This cascade reaction uses readily available and cheap sodium azide as a nitrogen source to gave 3-azido furoindolines and pyrrolidinoindolines under mild reaction conditions.

A new method for the catalytic enantioselective formal arylation of azlactones using quinones as the aromatic partner was developed for the first time. Under mild conditions, the domino Michael/aromatization/cyclization reaction worked well to afford the corresponding products in moderate to high yields with excellent enantioselectivities, some of which have promising cytotoxicity against cancer cells and antibacterial activities.

The copper-catalyzed cascade azidation–cyclization of tryptophols and tryptamines has been developed. This cascade reaction uses readily available and cheap sodium azide as a nitrogen source to gave 3-azido furoindolines and pyrrolidinoindolines under mild reaction conditions.

The first chiral phosphoric acid catalyzed highly diastereo- and enantioselective 1,3-dipolar cycloaddition reaction of azlactones and methyleneindolinones was disclosed. By using a BINOL-derived chiral phosphoric acid as the catalyst, azlactones were activated as chiral anti N-protonated 1,3-dipoles to react with methyleneindolinones to yield biologically important 3,3′-pyrrolidonyl spirooxindole scaffolds in high yields, with good-to-excellent diastereo- and enantioselectivity.

A new method for the catalytic enantioselective formal arylation of azlactones using quinones as the aromatic partner was developed for the first time. Under mild conditions, the domino Michael/aromatization/cyclization reaction worked well to afford the corresponding products in moderate to high yields with excellent enantioselectivities, some of which have promising cytotoxicity against cancer cells and antibacterial activities.

A catalyst-controlled switch of regioselectivity in asymmetric allylic alkylation of oxazolones with MBHCs was described. The SN2′–SN2′ reaction catalysed by a quinine-derived base produced γ-selective secondary allylic oxazolone derivatives, whereas the addition–elimination reaction catalysed by an amino acid-derived bifunctional urea catalyst provided β-selective primary adducts.

This review summarizes the recent advances in the field of asymmetric dearomatization of phenols and their applications in the total synthesis of some complex natural products. The dearomatization discussed here includes metal catalysed direct dearomatization, organocatalytic dearomatization and hypervalent iodine mediated dearomatization.