19174-61-9Relevant academic research and scientific papers
New Homochiral Ligands Bearing Nonstereogenic Chirotopic Centers. Lithiated N,N′-Dialkylureas as Chiral Bases and Sterically Crowded Phosphines for Asymmetric Catalysis
Graf, Claus-Dieter,Malan, Christophe,Harms, Klaus,Knochel, Paul
, p. 5581 - 5588 (2007/10/03)
The synthesis of new homochiral pseudo-C2-symmetrical ligands of type 1 bearing a nonstereogenic chirotopic center is reported. Two such structural units are combined in the ureas 2 and 10, which proved to be useful for enantioselective deprotonation and alkylation of ketones (up to 88% ee). The monophosphine 3 induced a high enantiomeric excess in the Pd-catalyzed allylation of dimethyl malonate (up to 73% ee). Furthermore, we have shown that the achiral sterically crowded alkyl diphosphine 23 efficiently stabilized Pd(0) at high temperatures.
REGIOSELECTIVE REPLACEMENT OF THE HYDROXY GROUP IN ALCOHOLS BY MEANS OF TRIHALOACETIC DERIVATIVES IN PRESENCE OF TRIPHENYLPHOSPHINE
Matveeva, E. D.,Yalovskaya, A. I.,Cherepanov, I. A.,Bundel', Yu. G.,Kurts, A. L.
, p. 1409 - 1415 (2007/10/02)
The investigation of the reactions of trichloroacetonitrile with 2-decanol, 2-methyl-3-octanol, 2,4-dimethyl-3-pentanol, and 2,2-dimethyl-1-propanol in presence of triphenylphosphine shows that the formation of alkyl chlorides from the corresponding alcohols goes regiospecifically: Even for 2,4-dimethyl-3-pentanol the amount of the isomeric chloride does not exceed 1percent, while neopentyl alcohol is converted into neopentyl chloride in 95percent yield.On the introduction of "external" nucleophiles (iodide and thiocyanate ions) into the reaction mixture the predominating reaction product is the alkyl chloride.As a result of the reaction of bromotrichloromethane with 1-nonanol and triphenylphosphine a mixture of the alkyl chloride and the alkyl bromide is formed.
DECOMPOSITION DES ESTERS DE LA N-HYDROXYTHIOPYRIDONE-2. SYNTHESE DE QUELQUES NOUVEAUX HALOGENURES SECONDAIRES ET TERTIAIRES ENCOMBRES.
Stofer, Edmond,Lion, Claude
, p. 623 - 628 (2007/10/02)
Hindered α,α-disubstituted and α,α,α-trisubstituted acyl chlorides give with N-hydroxy-2-thiopyridone, the corresponding esters.The decomposition of this compound in tetrachloromethane or in bromotrichloromethane as solvent and halogen atom source results in the formation of new very hindered secondary R1R2CHX (R1 = iPr or tBu; R2 = iPr or tBu; X = Cl or Br) and tertiary R1R2R3CX (R1 = R2 = R3 = iPr; R1 = tBu, R2 = iPr, R3 = Et or Me, X = Cl) alkyl halides.
