Photocatalyzed Cyanodifluoromethylation of Alkenes

Abstract

Difluoromethylation is astraightforwardand widely applied strategy used to incorporate HCF 2 into organic molecules.Incontrast, cyanation reagents are typically volatile or highly toxic,o rt hey require harsh reaction conditions. Incorporation of both CN and HCF 2 into organic molecules, such as alkenes,isaworthwhile but challenging task. Amethod for photocatalyzed cyanodifluoromethylationo fa lkenes has been developed, which employs aP h 3 P + CF 2 CO 2 À /NaNH 2 (or NH 3 )r eagent system. Ph 3 P + CF 2 CO 2 À functions as both the HCF 2 and CN carbon source.Acyanide anion is generated in situ under mild conditions,therebyavoiding the use of toxic cyanation reagents.The photocatalytic method permits cyanodifluoromethylation of ar ange of alkenes under mild room temperature conditions.T he CN group within the products may be further derivatized by standardmethods.

Visible-Light-Induced Difunctionalization of Styrenes: Synthesis of N-Hydroxybenzimidoyl Cyanides

“…26 The cyano substrate (2a) on treatment with NaN 3 is transformed to a tetrazole moiety (2e) without affecting the oxime functionality. 27 In conclusion, a visible-light-mediated synthesis of Nhydroxybenzimidoyl cyanides have been accomplished from styrenes in the presence of organic photoredox catalyst. The bifunctionalized moiety possesses two important functionalities, viz, an oxime and a nitrile group, which originate from tert-butyl nitrite and ammonium acetate, respectively.…”

“…Furthermore, the treatment of ( 2a ) with a phenylboronic acid in the presence of Pd­(II) catalyst, both the oxime and cyano functionality were converted to keto group ( 2d ) with concurrent incorporation of a phenyl group . The cyano substrate ( 2a ) on treatment with NaN 3 is transformed to a tetrazole moiety ( 2e ) without affecting the oxime functionality …”

A Readily Available Trifluoromethylation Reagent and Its Difunctionalization of Alkenes

“…Our previous work showed that the difluoromethylphosphonium salt (Ph 3 P + CF 2 H X − ) is easy to reduce by photocatalysis to realize the difunctionalization of olefins. 14 The redox potential of TFSP (E p red = −0.830 V vs SCE; see the SI) measured by cyclic voltammetry showed that it may have similar photoredox properties as Ph 3 P + CF 2 H X − . Then, we investigated the photocatalyzed azido-trifluoromethylation of TFSP with alkenes.…”

Synthesis of difluoromethylated allenes through trifunctionalization of 1,3-enynes

“…Over the past few decades, many difluoromethylation reactions have been successfully developed, enabling facile synthesis of different types of difluoromethylated compounds. Most commonly, the CF 2 H group (or CF 2 R group) is accessed from a CF 2containing building block or agent [14][15][16][17][18][19][25][26][27][28][29][30][31] . For example, the syntheses of difluoromethylated allenes typically require the use of difluoromethyl metal compounds [32][33][34][35] .…”