75088-70-9Relevant articles and documents
BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
Li, Xuan,He, Jianghua,Zhang, Yuetao
supporting information, p. 11019 - 11027 (2018/09/06)
For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
Fries rearrangement of aryl formates: A mechanistic study by means of 1H, 2H, and 11B NMR spectroscopy and DFT calculations
Bagno, Alessandro,Kantlehner, Willi,Kress, Ralf,Saielli, Giacomo,Stoyanov, Edmont
, p. 9331 - 9340 (2007/10/03)
(Figure Presented) 1H, 2H, and 11B NMR spectroscopy has been used to study the mechanism of the Fries rearrangement of aryl formates promoted by boron trichloride by monitoring both the substrate and the Lewis acid. DFT calculations were employed to investigate the energetics of several reaction paths and to calculate NMR chemical shifts of key intermediates and products. After the formation of a 1:1 substrate - Lewis acid adduct, the rearrangement proceeds in two steps, beginning with the cleavage of the ester bond and the release of formyl chloride in situ, which, in turn, acts as a formylating agent, introducing an aldehydic functionality into the aromatic ring. The high regioselectivity (only the ortho product is obtained) is also accounted for by the proposed intermolecular, Lewis acid-assisted mechanism.