124242-73-5Relevant academic research and scientific papers
Traceless Protection for More Broadly Applicable Olefin Metathesis
Mu, Yucheng,Nguyen, Thach T.,van der Mei, Farid W.,Schrock, Richard R.,Hoveyda, Amir H.
, p. 5365 - 5370 (2019)
An operationally simple in situ protection/deprotection strategy that significantly expands the scope of kinetically controlled catalytic Z- and E-selective olefin metathesis is introduced. Prior to the addition of a sensitive Mo- or Ru-based complex, treatment of a hydroxy- or a carboxylic-acid-containing olefin with commercially available HB(pin) or readily accessible HB(trip)2 (pin=pinacolato, trip=2,4,6-tri(isopropyl)phenyl) for 15 min is sufficient for efficient generation of a desired product. Routine workup leads to quantitative deprotection. A range of stereochemically defined Z- and E-alkenyl chlorides, bromides, fluorides, and boronates or Z-trifluoromethyl-substituted alkenes with a hydroxy or carboxylic acid group were thus prepared in 51–97 % yield with 93 to >98 % stereoselectivity. We also show that, regardless of whether a polar functional unit is present or not, a small amount of HB(pin) may be used to remove residual water, significantly enhancing efficiency.
Hindered Organoboron Groups in Organic Chemistry. Part 22. Some Interesting Properties of 2,4,6-Triisopropylphenylborane (Tripylborane, TripBH2, A New Useful Monoarylborane
Smith, Keith,Pelter, Andrew,Jin, Zhao
, p. 395 - 396 (2007/10/02)
2,4,6-Triisopropylphenylborane (tripylborane, TripBH2) is a solid, stable, hydroborating agent that hydroborates monosubstituted alkenes to give either TripBHR1 or TripBR12.TripBHR1 can be converted into mixed boranes TripBR1R2 (R1,R2 = primary alkyl, Rp) and TripBRpRs and TripBRs2 are also readily available.Oxidation of these products gives the corresponding alcohols in excellent yields, with a high selectivity for alkan-1-ols in the cases of groups derived from alk-1-enes.Cyanidation of TripBR2 proceeds to give ketones without migration of the aryl group.This establishes the low migratory aptitude of the aryl group and also that no scrambling of alkyl groups occurs.The tripyl group of TripBRp2 can be selectively removed.
Synthesis of the monomeric HBTrip2 (trip = 2,4,6-i-Pr3C6H2) and the X-ray crystal structures of [HBMes2]2 (Mes = 2,4,6-Me3C6H2) and HBTrip2
Bartlett, Ruth A.,Dias, H. V. Rasika,Olmstead, Marilyn M.,Power, Philip P.,Weese, Kenneth J.
, p. 146 - 150 (2008/10/08)
The synthesis and spectroscopic properties of HBTrip2 (1) and the X-ray crystal structures of 1 and the dimeric species [HBMes2]2 (2) are described. The synthesis of 1 was carried out by treatment of Me2S·BHCl2 with 2 equiv of TripMgBr in THF solution. Standard workup gave 1 as a colorless crystalline material that exhibited a broad singlet at 73.5 ppm downfield in the 11B NMR spectrum. X-ray data confirmed a monomeric structure with a planar boron center and a wide CBC angle of 128.0 (4)°. The less sterically encumbered 2 was prepared according to a literature procedure. The X-ray crystal structure reveals a dimeric structure with the expected bridging hydrogens. The compounds of 1 and 2 are the first diorganoboranes to be structurally characterized by X-ray crystallography. In addition, the structure of 1 represents the first structural characterization of a monomeric diorganoborane. Crystal data at 225 K for 1 or 140 K for 2, with Mo Kα (λ = 0.71069 A?) radiation: 1, monoclinic, a = 11.116 (4) A?, b = 14.869 (5) A?, c = 17.321 (6) A?, β = 100.19 (3)°, Z = 4, space group P21/c, R = 0.093; 2, monoclinic, a = 12.254 (6) A?, b = 7.768 (2) A?, c = 16.785 (6) A?, β = 109.43 (3)°, Z = 2, space group P2/n, R = 0.047.
