Visible‐Light‐Induced Difluoropropargylation Reaction with Benzothiazoline as a Reductant

Abstract

The difluoropropargyl group is a useful moiety for biological applications such as in vivo click chemistry for molecular imaging techniques. Silyl‐protected bromodifluoropropyne is an important difluoropropargylation reagent with previously unexplored radical reactivity. Herein, we report visible‐light‐induced thiyl‐radical‐catalyzed hydrodifluoropropargylation reactions between silyl‐protected bromodifluoropropyne and alkenes in the presence of benzothiazoline as a critical reductant.magnified image

Recent Advances in Synthesis of Difluoromethylene Phosphonates for Biological Applications

“…However, as was shown by Cheng and co‐workers, thiyl radicals generated from diphenyl disulfide under visible light and in the presence of benzothiazoline [106] can activate BrCF 2 P(O)(OEt) 2 toward radical addition to an unactivated C=C bond without the need for a transition metal complex (Scheme 23). [107] …”

Iron-Catalyzed Photoredox Intermolecular Dearomatization of Benzothiazoles with Alkanes

“…It has a hydrothiazole ring is a key structural motif in a variety of areas, including natural products, pharmaceutical chemistry, − and material science , (Scheme a). In addition, benzothiazoline, as an organic reductant, is widely used for organocatalytic transfer hydrogenation, such as the construction of chiral amines and the enantioselective synthesis of cis-cyclopropanes . Moreover, benzothiazoline derivatives as versatile reagents can achieve radical hydroalkylation and hydroacylation of alkenes (Scheme b).…”

Kinetic Studies of Hantzsch Ester and Dihydrogen Donors Releasing Two Hydrogen Atoms in Acetonitrile

“…The thermodynamic parameters on 20 possible elementary steps of Hantzsch ester (HEH 2 ), benzothiazoline (BTH 2 ), and dihydrophenanthridine (PDH 2 ) releasing two hydrogen atoms or ions have also been measured or derived from the related thermodynamic data using Hess’ law in acetonitrile . These three organic compounds are dihydrogen donors usually used to reduce olefins, aldehydes, ketones, imines, alkynes, and quinolines and have received wide attention owing to their study and application prospects in academia and industry. − In addition to these three dihydrogen donors, 2-benzylmalononitrile, 2-(9 H -fluoren-9-yl)­malononitrile, 2-benzyl-1H-indene-1,3­(2 H )-dione, 5-benzyl-2,2-dimethyl-1,3-dioxane-4,6-dione, 5-benzyl-1,3-dimethylpyrimidine-2,4,6­(1 H ,3 H ,5 H )-trione, ethyl 2-cyano-2-(9 H -fluoren-9-yl)­acetate, diethyl 2-(9 H -fluoren-9-yl)­malonate, and the derivatives (Scheme ) are also good dihydrogen donors. They are very popular in synthesis, catalysis, medicinal chemistry, and biochemistry. − Since they are all good reductants in organic synthesis and industrial production, it is necessary and urgent to study their actual dihydrogen-donating abilities in kinetics quantitatively.…”