Bipyridine Ligand-Promoted cis-Selective Hydroboration of Alkynes with Chromium Catalysis

Abstract

The chromium-catalyzed hydroboration of alkynes under mild conditions was reported. Low-cost chromium(III) chloride combined with 4,4'-di-tert-butyl 2,2'-bipyridine as the ligand and magnesium as the reductant shows high reactivity, which can catalyze and promote the hydroboration of alkynes with pinacolborane, thereby providing a strategy to form borylated olefins at ambient temperature.

Water-promoted defluorinative synthesis of fluoroalkylated 1,5-diazapentadienes by using (NH4)2CO3 as an NH2 and NH source

“…On the basis of the abovementioned experimental observations and previous literature, 14–22 two possible reaction mechanisms for the H 2 O-promoted and (NH 4 ) 2 CO 3 -enabled deiodoamination-defluoroiminization cascade of perfluoroalkyl alkenes is proposed in Scheme 3. Initially, perfluoroalkyl alkene 1 readily undergoes S N V-type C(sp 2 )–I bond displacement with a molecule of NH 3 to generate enamine B .…”

“…14 Within this context, the selective displacement of one or two C(sp 3 )–F bonds in fluoroalkyl alkenes represents an emerging method to access diverse mono-fluorinated or difluorinated frameworks, which are difficult to synthesize by direct fluorination. 15 Despite the remarkable achievements made before, to our knowledge, defluorinative iminization by means of selective C(sp 3 )–F bond cleavage of fluorinated allylic synthons for the synthesis of a 1,5-diazapentadiene system incorporating a fluoroalkyl moiety, accompanied by the interconversion of other functional groups and simultaneous multiple bond formation, remains unexplored (Fig. 1C).…”

Stereoselective hydrodefluorination of CF3-substituted alkenes and gem-difluoroalkenes by H−

“…Fluorine-substituted alkenes play a crucial role not only in enabling the synthesis of high-value organofluorine compounds, 4 but also in various applications related to drug discovery. 5 Significant progress has been made in activating C–F bonds in fluoroalkenes, forming C–C, C–O, or C–N bonds.…”

Transition-Metal-Free Hydrodefluoroamination of Trifluoromethyl Enones for the Synthesis of α-Fluoroenamides

“…Readily available α-trifluoromethyl alkenes have been demonstrated as robust and ideal substrates for the construction of oligofluorinated or nonfluorinated skeletons with structural diversity and complexity . Consequently, diverse gem -difluoroalkenes, allyl fluorides, and monofluorinated heterocycles become easily accessible through γ- or ipso -selective cleavage of a single C–F bond and a sequential two-fold C–F bond activation procedure (Scheme A).…”