51795-76-7Relevant academic research and scientific papers
Copper-Mediated and -Catalyzed o-DPPB-Directed Allylic Substitution
Breit, Bernhard,Demel, Peter
, p. 429 - 432 (2001)
Complete control of chemo-, regio- and stereoselectivity in the course of copper-catalyzed and -mediated allylic substitution could be obtained with me ortho-diphenylphosphanyl (o-DPPB) function as a reagent-directing leaving group. Complete chirality transfer by way of a syn-addition process has been achieved for cyclic and acyclic systems. Readily available Grignard reagents may be employed as nucleophiles and the directing o-DPPB group can be recovered quantitatively. The reaction requires neither cooling nor an excess of organometallic reagent.
Zinc homologation-elimination reaction of α-sulfinyl carbanions as a new route to olefins
Abramovitch, Adi,Marek, Ilan
experimental part, p. 4924 - 4931 (2009/05/27)
α-Lithiosulfinyl carbanions react either intermolecularly, after transmetalation into an organocopper derivative in an SN2-type process, with zinc carbenoids, or intramolecularly by higher-order zincates through a tandem zinc homologation-β-elimination reaction into the corresponding alkenes. α,α- and α,β-Disubstituted alkenes can also be produced through these two methodologies. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
O-DPPB-directed copper-mediated and -Catalyzed allylic substitution with grignard reagents
Demel, Peter,Keller, Manfred,Breit, Bernhard
, p. 6669 - 6683 (2008/09/16)
The ortho-diphenylphosphanylbenzoyl (o-DPPB) group was explored as a directing leaving group in copper-mediated and copper-catalyzed allylic substitution with Grignard reagents. Complete control of chemo-, regio- and stereoselectivity with complete syn-1,3-chirality transfer was observed as a result of the directed nature of the reaction. No excess of or ganometallic reagent is required and the directing group can be recovered quantitatively. Coordination studies in the solid state and in solution have shown that two substrates are bound via the phosphine function of the directing group at copper. Dynamic NMR experiments in solution are in agreement with a ligand-exchange process at copper, a prerequisite for the development of a substoichiometric process.
Eleminations from 1-Phenyl-2-alkyl Tosylates Promoted by MeONa in MeOH. Steric Effects in Alkene-forming Elimination
Cho, Bong Rae,Han, Man So
, p. 105 - 108 (2007/10/02)
Reactions of PhCH2CH(OTs)R i (3), Bus (4), But (5)> with MeONa in MeOH have been studied.The reactions produce both conjugated and unconjugated alkenes.The yields of the conjugated alkenes are nearly the same for 1-4, while the E/Z ratios depend strongly upon the α-alkyl group.The rates of eliminations forming the conjugated E alkenes are decreased by a bulkier alkyl group as indicated by the relative rate of 1, 0.8, 0.7, 0.6, 0.2 for 1, 2, 3, 4, 5, respectively.On the other hand, the relative rates for the formation of the unconjugatedalkenes are 1, 1.7, 2.8, 1.9 for 1, 2, 3, 4, respectively, indicating that the rate increases with the double bond stabilizing ability of the alkyl groups and decreases with their steric effect.From these results, the relative steric effect of the α- and β-alkyl groups in alkene-forming elimination is assessed.
