Stereogenic trifluoromethyl‐substituted carbon centers are highly sought‐after moieties in pharmaceutical and agrochemical discovery. Here, we show that lithiation–borylation reactions of 2‐trifluoromethyl oxirane give densely functionalized and highly versatile trifluoromethyl‐substituted α‐tertiary boronic esters. The intermediate boronate complexes undergo the desired 1,2‐rearrangement of the carbon‐based group with complete retentive stereospecificity, a process that was only observed in non‐polar solvents in the presence of TESOTf. Although the trifluoromethyl group adversely affects subsequent transformations of the α‐boryl group, Zweifel olefinations provide trifluoromethyl‐bearing quaternary stereocenters substituted with alkenes, alkynes and ketones.

The first successful gold(I)-catalyzed reaction of aryl aldehydes with trimethyl(arylethyn-

The one‐pot sequential coupling of benzylamines, boronic esters, and aryl iodides has been investigated. In the presence of an N‐activator, the boronate complex formed from an ortho ‐lithiated benzylamine and a boronic ester undergoes stereospecific 1,2‐metalate rearrangement/anti‐S N 2′ elimination to form a dearomatized tertiary boronic ester. Treatment with an aryl iodide under palladium catalysis leads to rearomatizing γ‐selective allylic Suzuki–Miyaura cross‐coupling to generate 1,1‐diarylalkanes. When enantioenriched α‐substituted benzylamines are employed, the corresponding 1,1‐diarylalkanes are formed with high stereospecificity.

The catalytic activation of alkynylsilanes towards 2-halo-1alkoxyalkyl arenes gives -halo-substituted alkynes. It involves the chemoselective substitution of an alkoxyde by an alkyne in the presence of a neighbour C(sp 3)-Br bond in a cationic CC bondforming event. Two complementary protocols to accomplish this new transformation are reported. The outcome of a direct approach based on mixing the precursors with a freshly prepared solution of the active catalytic species (TMSNTf2) is compared with an alternative based on smooth releasing the required silyliun ions upon selective activation of the alkyne by gold(I) (JohnPhosAuNTf2). The two approaches gave satisfactory results to access this otherwise elusive alkynylation process, which furnishes 4-bromo-substituted alkynes and tolerates various functional groups.

The one-pot sequential coupling of benzylamines, boronic esters,a nd aryl iodides has been investigated. In the presence of an N-activator,the boronate complex formed from an ortho-lithiated benzylamine and aboronic ester undergoes stereospecific 1,2-metalate rearrangement/anti-S N 2' elimination to form ad earomatized tertiary boronic ester.T reatment with an aryl iodide under palladium catalysis leads to rearomatizing g-selective allylic Suzuki-Miyaura cross-coupling to generate 1,1-diarylalkanes.When enantioenriched a-substituted benzylamines are employed, the corresponding 1,1-diarylalkanes are formed with high stereospecificity. Scheme 1. Access to 1,1-diarylalkanes.

Stereogenic trifluoromethyl‐substituted carbon centers are highly sought‐after moieties in pharmaceutical and agrochemical discovery. Here, we show that lithiation–borylation reactions of 2‐trifluoromethyl oxirane give densely functionalized and highly versatile trifluoromethyl‐substituted α‐tertiary boronic esters. The intermediate boronate complexes undergo the desired 1,2‐rearrangement of the carbon‐based group with complete retentive stereospecificity, a process that was only observed in non‐polar solvents in the presence of TESOTf. Although the trifluoromethyl group adversely affects subsequent transformations of the α‐boryl group, Zweifel olefinations provide trifluoromethyl‐bearing quaternary stereocenters substituted with alkenes, alkynes and ketones.

Addition of catalytic amounts of bistriflimide triggers useful coupling reactions of benzyl acetates with trimethyl(alkynyl)silanes and trimethyl(alkoxy)silanes to afford propargyl arenes and benzyl alkyl ethers, respectively. The added acid assists the release of reactive trimethylsilylium ion into the reaction media, which were found to act as the ultimate catalytic species responsible for the C−C and the C−O forming steps. The cationic nature of these coupling processes is documented.

Gold(I)-Catalyzed Bis-Alkynylation Reaction of Aromatic Aldehydes withAlkynylsilanes. -The first successful gold(I)-catalyzed reaction of aryl aldehydes with alkynylsilanes to furnish bis-alkynylated derivatives is reported. Key C-C bond-forming events involved in the catalytic cycle are analyzed. Under similar conditions, the reaction fails for aliphatic aldehydes such as hexanal but gives a mono-alkynylated product in moderate yield after solvent change (not shown). -(RUBIAL, B.; BALLESTEROS, A.; GONZALEZ*, J. M.; Adv. Synth. Catal. 355 (2013) 17, 3337-3343, http://dx.