Photocatalytic Coupling Reactions Of Potassium Alkyltrifluoroborates

Alkylboron reagents are powerful and useful building blocks in organic synthesis.By comparison with other C(sp3)organometallics(e.g.,alkylmagnesium,alkylzinc,alkytin,and alkylindium reagents),alkylboron reagents are easy to purify,less toxic,and typically air and moisture stable.Numerous examples of the transformations of alkylboron reagents into other functional groups have been reported,including-OH,halides,-CF3,-SCF3,and-NH2.We are interested in the development of some new coupling reactions of alkylboron reagents by photoredox catalysis.Nitrile-containing molecules not only constitute many medicinally and biologically important compounds,but also can be utilized as synthetic intermediates for generating other useful functional groups such as carboxylic acids,esters,amines,and amides.We describes the deboronative cyanation of potassium alkyltrifluoroborates via photoredox catalysis.Our new reaction offers a general,convenient,and efficient protocol for rapid access to primary,secondary,and even tertiary alkyl nitriles from easily prepared alkyltrifluoroborates using the readily available cyanation reagent p-toluenesulfonyl cyanide.Pyridine N-oxides and their functionalized derivatives are abundant structural components of biologically active and medicinally important compounds.In recent years,considerable efforts have been devoted to developing new methods for the functionalization of pyridine N-oxides.We reports direct ortho-selective C-H alkylation of pyridine N-oxides via visible-light photoredox catalysis.Our new reaction uses a readily available simple photocatalyst and shows good functional-group compatibility,thus enabling efficient synthesis of a variety of ortho-alkylated pyridine N-oxides.