96308-15-5Relevant academic research and scientific papers
Enantioselective Bromo-oxycyclization of Silanol
Xia, Zilei,Hu, Jiadong,Shen, Zhigao,Wan, Xiaolong,Yao, Qizheng,Lai, Yisheng,Gao, Jin-Ming,Xie, Weiqing
, p. 80 - 83 (2016)
Relying on the nucleophilicity of silanol for building up silicon-incorporated scaffold with an enantiopure tetrasubstituted carbon center remains elusive. In this report, asymmetric bromo-oxycyclization of olefinic silanol by using chiral anionic phase-transfer catalyst is described. This protocol provided a facile entry to a wide arrangement of enantiopure benzoxasilole in moderate to excellent enantioselectivities depending on the unique reactivity of bromine/N-benzyl-DABCO complex.
Enantioselective synthesis of 1-aminoindene derivativesviaasymmetric Br?nsted acid catalysis
Wu, Xiang,Ding, Du,Zhang, Ying,Jiang, Hua-Jie,Wang, Tao,Zhao, Li-Ping
supporting information, p. 9680 - 9683 (2021/09/30)
We describe a catalytic asymmetric iminium ion cyclization reaction of simple 2-alkenylbenzaldimines using a BINOL-derived chiralN-triflyl phosphoramide. The corresponding 1-aminoindenes and tetracyclic 1-aminoindanes are formed in good yields and high enantioselectivities. Further, the chemical utility of the obtained enantiopure 1-aminoindene is demonstrated for the asymmetric synthesis of (S)-rasagiline.
A Transient Directing Group Strategy Enables Enantioselective Multicomponent Organofluorine Synthesis
Liu, Zhonglin,Oxtoby, Lucas J.,Liu, Mingyu,Li, Zi-Qi,Tran, Van T.,Gao, Yang,Engle, Keary M.
supporting information, p. 8962 - 8969 (2021/07/01)
The vicinal fluorofunctionalization of alkenes represents an expedient strategy for converting feedstock olefins into valuable fluorinated molecules and as such has garnered significant attention from the synthetic community; however, current methods remain limited in terms of scope and selectivity. Here we report the site-selective palladium-catalyzed three-component coupling of alkenylbenzaldehydes, arylboronic acids, and N-fluoro-2,4,6-trimethylpyridinium hexafluorophosphate facilitated by a transient directing group. The synthetically enabling methodology constructs vicinal stereocenters with excellent regio-, diastereo-, and enantioselectivities, forging products that map onto bioactive compounds.
Oxidative cyclizations in a nonpolar solvent using molecular oxygen and studies on the stereochemistry of oxypalladation
Trend, Raissa M.,Ramtohul, Yeeman K.,Stoltz, Brian M.
, p. 17778 - 17788 (2007/10/03)
Oxidative cyclizations of a variety of heteroatom nucleophiles onto unactivated olefins are catalyzed by palladium(II) and pyridine in the presence of molecular oxygen as the sole stoichiometric oxidant in a nonpolar solvent (toluene). Reactivity studies of a number of N-ligated palladium complexes show that chelating ligands slow the reaction. Nearly identical conditions are applicable to five different types of nucleophiles: phenols, primary alcohols, carboxylic acids, a vinylogous acid, and amides. Electronrich phenols are excellent substrates, and multiple olefin substitution patterns are tolerated. Primary alcohols undergo oxidative cyclization without significant oxidation to the aldehyde, a fact that illustrates the range of reactivity available from various Pd(II) salts under differing conditions. Alcohols can form both fused and spirocyclic ring systems, depending on the position of the olefin relative to the tethered alcohol; the same is true of the acid derivatives. The racemic conditions served as a platform for the development of an enantioselective reaction. Experiments with stereospecifically deuterated primary alcohol substrates rule out a "Wacker-type" mechanism involving anti oxypalladation and suggest that the reaction proceeds by syn oxypalladation for both mono- and bidentate ligands. In contrast, cyclizations of deuterium-labeled carboxylic acid substrates undergo anti oxypalladation.
Comparison of the Ease of Thermolysis of Ortho-Substituted Phenyl Azides Having α,β or β,γ Imine Functions
Smith, Peter A. S.,Budde, Gregory F.,Chou, Shang-Shing P.
, p. 2062 - 2066 (2007/10/02)
o-Azidobenzaldehyde benzylimine (7) thermolyzes 34 times faster than phenyl azide and 1.6 times faster than p-chlorobenzaldehyde o-azidoanil (8), whereas benzaldehyde (o-azidobenzyl)imine (9) and acetophenone (o-azidobenzyl)imines (10a-e) show little or no rate enhancement over phenyl azide.An electrocyclic mechanism can account for the rates of 7 and 8 relative to each other but not of 8 relative to phenyl azide; 9 and 10a-e appear to thermolyze by nitrene formation, even though a mechanism through intramolecular cycloaddition may in principle be available.A mechanism based on electrostatic effects in a dipolar transition state can corr elate the effects of different types of α,β-unsaturated ortho substituents.
