Late-stage guanine C8-H alkylation of nucleosides, nucleotides, and oligonucleotides via photo-mediated Minisci reaction.

Chemically modified nucleosi(ti)des and functional oligonucleotides (ONs, including therapeutic oligonucleotides, aptamer, nuclease, etc.) have been identified playing an essential role in the areas of medicinal chemistry, chemical biology, biotechnology, and nanotechnology. Introduction of functional groups into the nucleobases of ONs mostly relies on the laborious de novo chemical synthesis. Due to the importance of nucleosides modification and aforementioned limitations of functionalizing ONs, herein, we describe a highly efficient site-selective alkylation at the C8-position of guanines in guanosine (together with its analogues), GMP, GDP, and GTP, as well as late-stage functionalization of dinucleotides and single-strand ONs (including ssDNA and RNA) through photo-mediated Minisci reaction. Addition of catechol to assist the formation of alkyl radicals via in situ generated boronic acid catechol ester derivatives (BACED) markedly enhances the yields especially for the reaction of less stable primary alkyl radicals, and is the key to success for the post-synthetic alkylation of ONs. This method features excellent chemoselectivity, no necessity for pre-protection, wide range of substrate scope, various free radical precursors, and little strand lesion. Downstream applications in disease treatment and diagnosis, or as biochemical probes to study biological processes after linking with suitable fluorescent compounds are expected.

Palladium-catalyzed C-H olefination of uridine, deoxyuridine, uridine monophosphate and uridine analogues.

The palladium-catalyzed oxidative C-H olefinations of uridine, deoxyuridine, uridine monophosphate and uridine analogues are reported herein. This protocol provides an efficient, atom-economic and environmentally friendly approach to the synthesis of biologically important C5-alkene modified uracil/uridine-containing derivatives and pharmaceutical candidates.

Rh(II)/Chiral Phosphoric Acid-Cocatalyzed Enantioselective Synthesis of Spirooxindole-Fused Thiaindans.

An asymmetric strategy for the construction of chiral sulfur-containing spirooxindole-fused heterocycles was achieved via a rhodium(II)/chiral phosphoric acid-cocatalyzed reaction between 2-mercaptophenyl ketones and 3-diazooxindoles. With this method, a series of spirooxindole-thiaindan derivatives bearing two contiguous quaternary carbon stereogenic centers were obtained in high yields with high diastereoselectivities and high-to-excellent enantioselectivities.

Synthesis of γ-Sulfur-Substituted Ketones via Rh(II)/Sc(III) a Cocatalyzed Three-Component Reaction of Diazo Compounds with Thiophenols and Enones.

A facile method for the synthesis of γ-sulfur-substituted ketones is developed via a Rh(II)/Sc(III) cocatalyzed three-component reaction of diazo compounds with thiophenols and enones. With this method, different γ-sulfur-substituted ketones were obtained in moderate to high yields with good diastereoselectivities.

Enantioselective Synthesis of α-Mercapto-ß-amino Esters via Rh(II)/Chiral Phosphoric Acid-Cocatalyzed Three-Component Reaction of Diazo Compounds, Thiols, and Imines.

An enantioselective method for the synthesis of α-mercapto-ß-amino esters has been developed via a rhodium(II)/chiral phosphoric acid-cocatalyzed three-component reaction of diazo compounds, thiols, and imines. This transformation is proposed to proceed through enantioselective trapping of the sulfonium ylide intermediate generated in situ from the diazo compound and thiol by the phosphoric acid-activated imine. With this method, a series of α-mercapto-ß-amino esters were obtained in good yields with moderate to good stereoselectivities.

Efficient synthesis of sterically hindered arenes bearing acyclic secondary alkyl groups by Suzuki-Miyaura cross-couplings.

Bulky P,P=O ligands were designed to inhibit isomerization and reduction side reactions during the cross coupling between sterically hindered aryl halides and alkylboronic acids. Suzuki-Miyaura cross-couplings between di-ortho-substituted aryl bromides and acyclic secondary alkylboronic acids have been achieved with high yields. The method has also enabled the preparation of ortho-alkoxy di-ortho-substituted arenes bearing isopropyl groups in excellent yields. The utility of the synthetic method has been demonstrated in a late-stage modification of estrone and in the application to a new synthetic route toward gossypol.

2,2'-[(1E)-3-Phenyl-prop-2-ene-1,1-di-yl]bis-(3-hy-droxy-5,5-dimethyl-cyclo-hex-2-en-1-one).

In the title mol-ecule, C(25)H(30)O(4), the two cyclo-hexene rings adopt envelope conformations. The two hy-droxy groups are involved in the formation of intra-molecular O-H⋯O hydrogen bonds. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules related by translation along the axis a into chains.