Aminoborohydrides. 6. Diastereoselective reduction of the carbon-nitrogen double bond in chiral imines using lithium diethylaminoborohydride and lithium diisopropylaminoborohydride
作者:Joseph C. Fuller、Christopher M. Belisle、Christian T. Goralski、Bakthan Singaram
DOI:10.1016/s0040-4039(00)73507-6
日期:1994.7
enantiomerically enriched secondary amines. The yields of secondary amines from this procedure range from very good to essentially quantitative. The diastereomeric induction in the reduction of the carbon-nitrogen double bond with Li(Et)2NBH3 and Li(i-Pr)2NBH3 ranged from moderate to very good.
作者:Thomas C. Nugent、Mohamed El-Shazly、Vijay N. Wakchaure
DOI:10.1021/jo7021235
日期:2008.2.1
Reductive amination of prochiral unhindered 2-alkanones 1 with (R)- or (S)-alpha-MBA in the presence of Yb(OAc)(3) (50-110 mol %), Raney-Ni, and hydrogen (120 psi) results in increased diastereoselectivity for the amine products 2 (80-89% de) with good yield (80-87%). The increased de is based on comparison with the best previously reported de's when using (R)- or (S)-alpha-MBA, regardless of the strategy employed [stepwise (isolation of ketimines) or one-pot (reductive amination)], reducing agent examined, or achiral Lewis acid or Bronsted acid examined. An in situ cis- to trans-ketimine isomerization mechanism, promoted by Yb(OAC)(3), has been proposed to account for the observed increase in diastereoselectivity and suggests a new entry into the control of ketimine geometry.
A Dramatic Effect of Aryloxo Ligands on the Titanium-Catalyzed Hydroamination of Alkynes
作者:Vivek Khedkar、Annegret Tillack、Matthias Beller
DOI:10.1021/ol035653+
日期:2003.12.1
[GRAPHICS]The aryloxotitanium complex 1 is a highly chemo- and regioselective catalyst for intermolecular hydroamination of terminal alkynes. Branched imines are obtained in good to excellent yield (up to 99%) with various primary aromatic and aliphatic amines.
Sequential Reductive Amination-Hydrogenolysis: A One-Pot Synthesis of Challenging Chiral Primary Amines
作者:Thomas C. Nugent、Daniela E. Negru、Mohamed El-Shazly、Dan Hu、Abdul Sadiq、Ahtaram Bibi、M. Naveed Umar
DOI:10.1002/adsc.201100250
日期:2011.8
Difficult-to-access chiralprimaryamines were formed in good to high yield and ee using a rare example of a one-potsynthesis from prochiral ketones (sequentialreductive amination-hydrogenloysis). As a highlight we also demonstrate a one-potreductive amination-hydrogenolysis-reductive amination (five reactions) of ortho-methoxyacetophenone resulting in the chiral diamine 1-(2-methoxyphenyl)ethy
Routes to enantioenriched amines are outlined that employ reductive amination and carbanion addition methods. The strategies require either one or two reaction steps from prochiral carbonyl compounds for the synthesis of the corresponding chiral primary amines.