109433-73-0Relevant articles and documents
Boranes in Synthesis. 5. The Hydroboration of Enamines with Mono- and Dialkylboranes. Asymmetric Synthesis of β-Amino Alcohols of Moderate Enantiomeric Purity from Aldehyde Enamines
Fisher, Gary B.,Goralski, Christian T.,Nicholson, Lawrence W.,Hasha, Dennis L.,Zakett, Donald,Singaram, Bakthan
, p. 2026 - 2034 (1995)
The hydroboration of both acyclic and cyclic aldehyde and ketone enamines with such representative mono- and dialkylboranes as thexylborane and dicyclohexylborane, followed by an oxidative workup, yields the corresponding β-amino alcohols in good to excellent isolated yields.The hydroboration of ketone and aldehyde enamines with the asymmetric hydroboration reagents monoisopinocampheylborane (dIpeBH2) and diisopinocampheylborane (dIpc2BH) was also investigated. dIpc2BH is highly effective for the asymmetric hydroboration of acyclic aldehyde enamines, such as 1-(4-morpholino)-3-phenyl-1-propene and 1-(1-pyrrolidino)-1-octene.Oxidation of the intermediate trialkylborane furnishes the corresponding β-amino alcohols in 50-86percent ee.The stereogenic center of the carbinol carbon is consistently enriched in the R-enantiomer when dIpc2BH prepared from (+)-α-pinene is used as the hydroboration reagent.The enantiomeric excesses of the β-amino alcohols synthesized in this study were determined by HPLC using a chiral stationary phase.The absolute configuration of some of the β-amino alcohols synthesized in this study were determined by chiral HPLC comparison with authentic β-amino alcohols prepared from chiral epoxides of known absolute configuration.
Chemoenzymatic preparation of optically active trans-cyclohexane-1,2- diamine derivatives: An efficient synthesis of the analgesic U-(-)-50,488
Gonzalez-Sabin, Javier,Gotor, Vicente,Rebolledo, Francisca
, p. 5788 - 5794 (2007/10/03)
Stereoespecific syntheses of (±)-trans-N,N-cyclohexane-1,2-diamines ((±)-4a-g) were carried out from the corresponding (±)-trans-N,N- dialkylaminocyclohexanols by successive treatment with mesyl chloride and aqueous ammonia. The stereochemical outcome indicates the formation of a meso-aziridinium ion intermediate, Kinetic resolutions of diamines (±)-4 were efficiently accomplished in aminolysis reactions catalyzed by lipase B from Candida antarctica with ethyl acetate as the solvent and acyl donor. Acetamides and the remaining diamines, isolated as the benzyloxycarbonyl derivatives, were obtained with very high ee values (92-99%), One of the carbamates was used as a precursor of the analgesic U-(-)-50,488.
