14992-40-6Relevant articles and documents
Vibrational studies of trans-stilbenes--II. Infrared and Raman spectra of fluorinated trans-stilbenes
Meic, Z.,Guesten, H.
, p. 1021 - 1028 (1980)
Infrared and Raman spectra of trans-α-fluoro-stilbene, trans-α,α'-difluoro-stilbene, trans-4,4'-difluoro-stilbene and trans-2,2',3,3',4,4',5,5',6,6'-decafluoro-stilbene were recorded and are reported here for the first time.The assignments are proposed fo
Catalytic enantioselective allyl- and crotylboration of aldehydes using chiral diol·SnCl4 complexes. Optimization, substrate scope and mechanistic investigations
Rauniyar, Vivek,Zhai, Huimin,Hall, Dennis G.
supporting information; experimental part, p. 8481 - 8490 (2009/02/02)
We report a novel class of C2-symmetric chiral diols derived from the hydrobenzoin skeleton. The combination of these diols with SnCl 4 under Yamamoto's concept of Lewis acid assisted Bronsted acidity (LBA catalysis) leads to high levels of asymmetric induction in the allylboration of aldehydes by commercially available allylboronic acid pinacol ester 1a. The corresponding homoallylic alcohol products of synthetically useful aliphatic aldehydes are obtained in excellent yields with up to 98:2 er. This combined acid manifold is also efficient in catalyzing the diastereo- and enantioselective crotylboration of aldehydes, thus providing the propionate units in >95:5 dr and up to 98:2 er. The X-ray crystal structure of the optimal diol·SnCl4 complex, Vivol (4m)·SnCl 4, unambiguously shows the Bronsted acidic character of this LBA catalyst and its highly dissymmetrical environment. Further controls have ruled out a possible boron transesterification mechanism with the chiral diol and point to LBA catalyst-derived activation of the pinacol allylic boronates 1. Due to slow dissociation of the diol·SnCl4 complex, a small excess of diol is required in order to suppress a competing racemic cycle catalyzed by free SnCl4.
Diastereoselective synthesis of pinacols from aromatic aldehydes using the system pentacarbonyliron-hexamethylphosphoric triamide. Dual reactivity of pentafluorobenzaldehyde
Terent'ev,Vasil'eva,Chakhovskaya,Mysova,Kochetkov
, p. 518 - 521 (2008/02/02)
The system Fe(CO)5-HMPA effectively promotes diastereoselective reductive dimerization of aromatic aldehydes to the corresponding pinacols having preferentially or exclusively dl configuration. In the reaction with pentafluorobenzaldehyde, the product structure strongly depends on the presence of traces of moisture in the reaction system. Nauka/Interperiodica 2007.