254893-39-5Relevant academic research and scientific papers
Diastereoselective alkylation of α-amino-substituted benzyllithiums
Azzena, Ugo,Pilo, Luciano,Piras, Elisabetta
, p. 129 - 131 (2001)
Reductive lithiation of a distereoisomeric mixture of bicyclic oxazolidines followed by reaction with alkyl halides afforded aminoalcohols in a highly syn-selective fashion. Reductive lithiation occurs with racemization at the benzylic carbon atom; the observed diastereoselectivities are rationalized in terms of a pair of rapidly equilibrating diastereoisomeric organolithium intermediates, one of which reacts preferentially under appropriate reaction conditions.
Straightforward synthesis of [(2S,4R)-1-cyclohexyl-4-methylpiperidin-2-yl] methanol and [(2S,4R)-1-cyclohexyl-4-methylpiperidin-2-yl](diphenyl)methanol: Novel chiral ligands for the catalytic addition of diethylzinc to benzaldehyde to give rise to an extensive turn in the sense of asymmetric induction
Alvarez-Ibarra, Carlos,Lujan, Juan F. Collados,Quiroga-Feijoo, Maria L.
experimental part, p. 2334 - 2345 (2010/12/25)
Enantiopure [(2S,4R)-1-cyclohexyl-4-methylpiperidin-2-yl]methanol 5a and [(2S,4R)-1-cyclohexyl-4-methylpiperidin-2-yl]-(diphenyl)methanol 5b, new β-amino alcohols based on l-pipecolinic acid (homoproline), have been prepared straightforwardly from rac-alaninol and rac-2-amino-1,1-diphenylpropan- 1-ol, respectively. The described route constitutes as a model procedure for the preparation of other related C(4) or/and C(3)-substituted 2- piperidinylmethanols. The new chiral ligands have shown a singular behaviour on the stereocontrol of the benchmark reaction of benzaldehyde and diethylzinc compared with other C(4)-unsubstituted analogues prepared by ourselves from l-pipecolinic acid (compounds 5c, 5d, 5e and 5f). The catalytic activity, the sense of asymmetric induction and the degree of the enantioselectivity depend on the appropriate combination of the substituents on the structural scaffold, but also on the metal-alkoxide involved in the catalysis (zinc or lithium alkoxides). The enantioselective addition of diethylzinc to benzaldehyde mediated by ligands 5a and 5c has been studied with DFT methods. The theoretical evaluation was performed in connection with a working hypothesis based on the different loadings of cis- and trans-catalysts in the reaction medium.
Benzhydryl derivatives
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, (2008/06/13)
A compound of the formula (I): in which Z, R1, R2, R8, R10, R11, R12, R13 and R14 are each as defined in the description, or a salt thereof. The object compound of the
Diastereoselective lithiation and substitution of (S)-N-benzylprolinol and rac-N-benzylpiperidine-2-methanol via the carbamate esters: Kinetic resolution by means of (-)-sparteine-mediated deprotonation
Weber,Schwerdtfeger,Froehlich,Goehrt,Hoppe
, p. 1915 - 1924 (2007/10/03)
The (S)-N-benzylprolinol carbamate (S)-8 is deprotonated by sec- butyllithium with the removal of the pro-R-H and the intermediate lithium compound 10 is trapped by several electrophiles. Complete ul-diastereotopos- differentation is achieved irrespective
