Effective CF(3) transfer: Various electron-rich nitrogen heterocycles (pyrazoles, triazoles, and tetrazoles) can be directly N-trifluoromethylated by a hypervalent iodine reagent in an efficient manner. The optimized procedure, which includes an in situ silylation of the substrate followed by an acid-catalyzed CF(3) transfer, provides ready access to a series of new and previously challenging or inaccessible NCF(3) compounds.

A mild trifluoromethylation reaction of N,N‐disubstituted hydroxylamines that is tolerant towards a variety of functional groups, including nitriles, alcohols, ketones, esters, amides, imides, and nitrogen heterocycles, is reported. The key feature of this reaction is the activation of the CF3 reagent with either trimethylsilyl triflate or LiClO4 and partial or full deprotonation of the substrate with tetramethylguanidine or lithium diisopropylamide. Products were obtained in up to 80 % yield. Preliminary mechanistic studies suggested that the reaction follows a radical pathway in which the deprotonated hydroxylamine and a Lewis or Brønsted acid activated CF3 reagent engages in a single‐electron‐transfer step to generate a pair of radicals that recombine to afford the desired product. The trifluoromethylation procedure was successfully used in the modification of secondary nitrogen groups of pharmaceutically relevant targets (Fluoxetine and Mefloquine), which afforded new derivatives containing a novel N‐trifluoromethoxy moiety.

Polyolefins are important and broadly used materials. Their molecular microstructures have direct impact on macroscopic properties and dictate end-use applications. 13 C NMR is a powerful analytical technique used to characterize polyolefin microstructures, such as long-chain branching (LCB), but it suffers from low sensitivity. Although the 13 C sensitivity of polyolefin samples can be increased by about 5.5 times with a cryoprobe, when compared with a conventional broadband observe (BBO) probe, further sensitivity enhancement is in high demand for studying increasingly complex polyolefin microstructures. Toward this goal, distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (RINEPT) are explored. The use of hard, regular, and new short adiabatic 180°1 3 C pulses in DEPT and RINEPT is investigated. It is found that RINEPTs perform better than DEPTs and a sensitivity enhancement of 3.1 can be achieved with RINEPTs. The results of RINEPTs are further analyzed with statistics software JMP and recommendations for optimal usage of RINEPTs are suggested. An example of analyzing saturated chain ends in an ethylene−octene copolymer sample with a hard 180°1 3 C RINEPT pulse is demonstrated. It is shown that the experimental time can be further reduced in half because of faster proton relaxation, where the total experimental time is about 580 times shorter when compared to using a conventional method and a 10 mm BBO probe. A naturally abundant nitrogen-containing polyolefin is analyzed using 1 H− 15 N HMBC and, to our knowledge, is the first 1 H− 15 N HMBC presented in the field of polyolefin characterization. The relative amount of similar nitrogen-containing structures is quantified by two-dimensional integration of 1 H− 15 N HMBC. Two pragmatic technical challenges related to using high-sensitivity NMR cryoprobes are also addressed: (1) A new 1 H decoupling sequence Bi_Waltz_65_256pl is proposed to address decoupling artifacts in 13 C{ 1 H} NMR spectra which contain a strong 13 C signal with a high signal-to-noise ratio (S/N). (2) A simple pulse sequence that affords zero-slope spectral baselines and quantitative results is presented to address acoustic ringing that is often associated with high-sensitivity cryoprobe use.

A series of phosphorus ligands containing the 5,6,7,8-tetrafluoronaphthalen-1-yl group (NpF 4 ) has been prepared, starting from 1-bromo-5,6,7,8-tetrafluoronaphthalene. The coordination chemistry of diphenyl(5,6,7,8-tetrafluoronaphthalen-1-yl)phosphine (1) with Ir(III), Pd(II), Pt(II), Rh(I), Ir(I), and Au(I) has been investigated, focusing on a possible remote interaction of the fluorine atom at position 8 of the naphthyl group (F 1 ) with the metal center. The Ir(III) complex [IrCp*Cl 2 (1)] ( 12) displays a weak J(P,F 1 ) coupling constant of 8 Hz and no Ir-F 1 interaction. A cationic derivative, the formally coordinatively unsaturated [IrCp*Cl(1)]SbF 6 (13), is generated upon chloride abstraction. For this complex J(P,F 1 ) is 80 Hz and the Ir-F 1 distance is 2.956(2) A ˚. [MCl(η 3 -allyl)(1)] complexes (14, M = Pt; 15, M = Pd) display what is interpreted as a weaker M-F 1 interaction despite corresponding J(P,F 1 ) values of 67 and 98 Hz and M-F 1 distances of 3.069(2) and 2.995(2) A ˚, respectively. Similar considerations apply to the analogous Rh(I) and Ir(I) complexes [IrCl(COD)(1)] ( 18) and [RhCl(COD)( 1)] (19) (J(P,F 1 ) = 62 and 75 Hz and M-F 1 = 3.0744( 14) and 3.0997(8) A ˚, respectively). With the chiral enantiopure ligand (11bS)-4-(5,6,7,8-tetrafluoronaphthalen-1yl)dinaphtho[2,1-d:1 0 ,2 0 -f][1,3,2]dioxaphosphepine (10) analogous complexes were prepared. Ligand 10 is formally a derivative of 1 where the two phenyl groups have been replaced by a BINOL unit. In the case of [PtCl(η 3 -allyl)(10)] ( 16) and [RhCl(COD)( 10)] ( 21) the coupling between F 1 and the NMRactive nuclei 195 Pt and 103 Rh, respectively, was detected in 2D NMR heteronuclear correlation experiments.