Synthesis of gem-Difluorinated 2,3-Dihydrobenzofurans Using Freon-22 via [4 + 1] Annulation of Difluorocarbene and Antitumor Activity Evaluation.

As an inexpensive industrial chemical, chlorodifluoromethane (Freon-22), despite its relatively low reactivity, can serve as a practical CF2 source for the construction of gem-difluorinated ring structures. Here, we develop a protocol for the efficient assembly of valuable fluorinated 2,3-dihydrobenzofurans from the [4 + 1] annulation in good yields under basic conditions. The reliable practicability and scalability of the process have also been demonstrated by preparation at the multigram scale, late-stage modifications of pharmaceutical molecules, and potential antitumor potency.

Catalytic Asymmetric 1,3-Dipolar Cycloaddition of ß-Fluoroalkylated α,ß-Unsaturated 2-Pyridylsulfones with Nitrones for Chiral Fluoroalkylated Isoxazolidines and γ-Amino Alcohols.

2-Pyridylsulfone- and fluoroalkylated group-activated olefins underwent highly efficient diastereo- and enantioselective 1,3-dipolar cycloadditions across various aromatic and aliphatic nitrones in the presence of a chiral NiII /bis(oxazoline) catalyst. The process was tuned by 4 Šmolecular sieves, chiral bis(oxazoline) ligands, reaction solvents, and temperature. A wide array of optically pure fluoroalkylated isoxazolidines were obtained, thus facilitating the asymmetric synthesis of an enantioenriched α-trifluoromethylated γ-amino alcohol in gram-scale and a trifluoromethylated derivative of 1,3-oxazinan-2-one with potential pharmaceutical interest. A stereochemical model, based on the absolute configuration of one adduct and some control experiments, was postulated to account for the observed endo- and enantioselectivity.

The squaramide-catalyzed asymmetric Michael/cyclization tandem reaction for the synthesis of chiral trifluoromethylated hydroxyimino tetrahydrobenzofuranones.

An enantioselective synthesis of trifluoromethylated hydroxyimino tetrahydrobenzofuranones has been developed. 1,3-Dicarbonyl carbocyclic compounds react with ß-CF3-ß-disubstituted nitroalkenes in the presence of a chiral squaramide catalyst, providing efficient access to diverse hydroxyimino tetrahydrobenzofuranones featuring a trifluoromethyl group at the C3-position of an all-carbon quaternary stereocenter with good yields (up to 81%) and enantioselectivities (up to 89% ee).

Water gelation abilities of alkylbenzyltriazole-appended 2'-deoxyribonucleoside and ribonucleoside.

Alkylbenzyltriazole units covalently bonded onto uridine nucleosides were synthesized and their suitability for water gelation compared with 2'-deoxyuridine derivatives was tested.