76287-59-7Relevant academic research and scientific papers
Catalytic asymmetric carbong-carbon bond formation via allylic alkylations with organolithium compounds
Perez, Manuel,Fananas-Mastral, Martin,Bos, Pieter H.,Rudolph, Alena,Harutyunyan, Syuzanna R.,Feringa, Ben L.
experimental part, p. 377 - 381 (2012/01/06)
Carbon-carbon bond formation is the basis for the biogenesis of nature's essential molecules. Consequently, it lies at the heart of the chemical sciences. Chiral catalysts have been developed for asymmetric C-C bond formation to yield single enantiomers from several organometallic reagents. Remarkably, for extremely reactive organolithium compounds, which are among the most broadly used reagents in chemical synthesis, a general catalytic methodology for enantioselective C-C formation has proven elusive, until now. Here, we report a copper-based chiral catalytic system that allows carbon-carbon bond formation via allylic alkylation with alkyllithium reagents, with extremely high enantioselectivities and able to tolerate several functional groups. We have found that both the solvent used and the structure of the active chiral catalyst are the most critical factors in achieving successful asymmetric catalysis with alkyllithium reagents. The active form of the chiral catalyst has been identified through spectroscopic studies as a diphosphine copper monoalkyl species.
Synthesis of 4-nitrophenyl sulfones and application in the modified Julia olefination
Mirk, Daniela,Grassot, Jean-Marie,Zhu, Jieping
, p. 1255 - 1259 (2007/10/03)
4-Nitrophenyl (NP) sulfones have been successfully employed in the modified Julia olefination reaction with carbonyl compounds. The olefination reaction proceeds through a sequence of aldol addition, Smiles rearrangement, and elimination. The sulfones are easily prepared in high yields in a two-step sequence starting from inexpensive commercially available para- fluoronitrobenzenes via nucleophilic aromatic substitution by a mercaptane and subsequent oxidation under standard conditions. The modified Julia reaction between NP sulfones and a wide variety of aromatic aldehydes affords the corresponding styrenes, stilbenes and cinnamate derivatives in yields up to 97% and good stereoselectivities. A mechanistic rationale is advanced to explain the observed results. Georg Thieme Verlag Stuttgart.
Preparation and Properties of Tertiary p-Alkylarylphosphines containing Straight-chain Alkyl Groups
Franks, Stephen,Hartley, Frank R.
, p. 2233 - 2237 (2007/10/02)
A series of tris(p-alkylaryl)phosphines with straight-chain alkyl groups, P(p-C6H4-CnH2n+1)3 where n=2-9, have been prepared by reaction of phosphorus trichloride with the Grignard reagent derived from the corresponding p-bromoalkylbenzene.When n=2 and 3 the phosphines are crystalline solids, but for n>3 they are viscous oils up to n=9, which is a waxy solid.The phosphines have been characterised by microanalysis, and i.r., 1H and 31P n.m.r., and mass spectrometry.The p-substituted-arylphosphines are more sensitive than triphenylphosphine to air; aerial oxidation converts them exclusively into the corresponding phosphine oxides, in contrast to trialkylphosphines which are oxidised to a complex mixture of products.The complexing ability of the new phosphines (PAr3) is demonstrated by their ready displacement of 1,5-cyclo-octadiene (cod) from (M=Pd and Pt) to yield trans- and cis-, respectively.
