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A base-assisted dearomative [2 + 1] spiroannulation of p / o -bromophenols with activated olefins (methylenemalonates) to construct various cyclopropyl spirocyclohexadienone skeletons is reported. Furthermore, several other halophenols (X = Cl, I) were also tolerated in this process. Control experiments reveal a dearomative Michael addition of phenols at their halogenated positions to methylenemalonates, followed by intramolecular radical-based S RN 1 dehalogenative cyclopropanation. However, according to the density functional theory (DFT) calculations, an S N 2 dehalogenative cyclopropanation with the same low activation energy barrier should not be excluded. The utility of this method is showcased by gram-scale syntheses and transformations of the dearomatized products.

The desymmetrization of meso - vic -diols with a reversal of enantioselectivity catalyzed by chiral pyridine- N -oxides with l-proline as a single source of chirality is reported. With chiral 3-substituted ArPNO C2c and 2-substituted 4-(dimethylamino)pyridine- N -oxide C3b as catalysts, a wide range of monoesters were obtained with satisfactory results with a complete and controlled switch in stereoselectivity (up to 97:3 and 1:99 er). Chiral six-membered carbocyclic uracil nucleosides were generated with excellent enantioselectivities after derivatization. A series of control experiments and density functional theory (DFT) calculations supported that the reaction proceeded in a bifunctional activated manner, where the N -oxide groups and N-H proton of the amides were vital for catalytic reactivity and stereocontrol. The DFT calculation also supported the distance-directed switching of enantioselectivity, in which the l-prolinamide moiety moved from the C3 to C2 position on the pyridine ring, resulting in the H-bond interaction between the amide N-H and OH group of meso - vic -diol also shifted from one hydroxyl group to another.

A CuI-catalyzed C-N coupling reaction of 3-bromo-DMAP with l-prolinamides was conducted at 80 °C in 12-16 h, where the prolinamide's structure had an accelerating effect on the Ullmann-type reaction. This reaction was used to construct chiral 3-amino DMAP catalysts. Furthermore, enantioenriched DMAP analogue C8 was applied in an asymmetric Black rearrangement of 2-benzofuranylcarbonates, affording 3,3-disubstituted benzofuran-2-ones in up to 96% yield and 97% ee.

An efficient method to construct chiral acyclic nucleosides via Sharpless asymmetric dihydroxylation of N-allylpyrimidines or N-alkenylpurines is reported. A range of chiral acyclic nucleosides with two adjacent hydroxyl groups present on the side chains could be produced in good yields (up to 97% yield) and excellent enantioselectivities (90-99% ee). The synthetic utility of the reaction was demonstrated by the catalytic asymmetric synthesis of ( S)-Cidofovir and ( R)-Buciclovir.

A combined palladium- and photoredox-catalyzed monoselective arylation of 6-arylpurine nucleosides has been developed by employing purine as a directing group via the photoredox reaction, and many functional groups are well tolerated in this direct C-H arylation condition. Various of functionalized purines (nucleosides) which are potentially of great importance in medicinal chemistry could be obtained under visible light irradiation at room temperature within 4 h.

The organocatalytic asymmetric allylic etherification reaction of Morita-Baylis-Hillman carbonates and silanols was reported for the first time. With modified cinchona alkaloid (DHQD) 2 PYR as the catalyst, a series of aromatic, heterocyclic, or aliphatic Morita-Baylis-Hillman carbonates (25 examples) worked well with triphenylsilanol, affording the corresponding products in moderate to good yields (up to 98%), high regioselectivities (>20:1), and good enantioselectivities (up to 92%). When dimethylphenylsilanol was used as the nucleophile, the product was obtained in 60% yield and 87% ee.

A novel protocol to construct fluorescent purine-fused tricyclic products via intramolecular cyclization of N-propargyl-adenine has been developed. With CuBr as the catalyst, a series of purine-fused tricyclic products were obtained in good to excellent yields (19 examples, 75-89% yields). When R2 was a hydrogen atom in N-propargyl-adenines, the reactions only afforded the endocyclic double bond products. When R2 was an aryl group, the electron-donating groups favored the endocyclic double bond products, while the electron-withdrawing groups favored the exocyclic double bond products.

Purine-fused tricyclic derivatives have been synthesized via a copper-catalyzed domino Michael/oxidative cross-coupling reaction between adenines and nitroolefins for the first time. With air as the oxidant, this method has high regioselectivity, which provides a new route for constructing purine-nucleoside-conjugated systems with two newly formed C–N bonds. Meanwhile, purine nucleosides with an exocyclic amino group could be obtained easily by simple reduction, which may lead to potential applications in fluorescence recognition of various bases in vivo.

The one-pot and direct synthesis of 7,9-dialkylpurin-8-one analogues with broad substrate scope has been developed. This copper-catalyzed C-H oxidation reaction could avoid multistep synthesis of quaternary ammonium salts and expand the scope of halogenated alkanes. Moreover, benzimidazole derivatives are also applicable in the catalytic system.