Asymmetric Imine Hydroboration Catalyzed by Chiral Diazaphospholenes
作者:Matt R. Adams、Chieh-Hung Tien、Robert McDonald、Alexander W. H. Speed
DOI:10.1002/anie.201709926
日期:2017.12.22
first use of diazaphospholenes as chiral catalysts has been demonstrated with enantioselective iminehydroboration. A chiral diazaphospholene prepared in a simple three‐step synthesis from commercial materials has been shown to achieve the highest enantioselectivity for the hydroboration of alkyl imines with pinacolborane reported to date. Enantiomer ratios of up to 88:12 were obtained with low (2 mol %)
1,1′-Binaphthyldiamine-Based Lewis Bases as Readily Available and Efficient Organocatalysts for the Reduction of<i>N</i>-Aryl and<i>N</i>-Alkyl Ketimines
development of simple, low-cost, efficient, and sustainable routes to enantiomerically pure amines is a topic of extraordinary interest, specially in view of future industrial applications. In this context, we wish to report a chemical and stereochemical efficient synthesis of chiral amines through the Lewis base activated trichlorosilane reduction of ketimines. An organocatalyst, easily prepared in a single
Asymmetric organocatalytic reduction of ketimines with catecholborane employing a N-triflyl phosphoramide Brønsted acid as catalyst
作者:Dieter Enders、Andreas Rembiak、Matthias Seppelt
DOI:10.1016/j.tetlet.2012.11.055
日期:2013.2
The first asymmetric reduction of ketimines with catecholborane employing an enantiopure N-triflyl phosphoramide as the organocatalyst has been developed. Five mole % of the catalyst provides the corresponding secondary amines in very good to almost quantitative yields and good enantioselectivities up to 86:14 e.r. under mild reaction conditions.
The influence of the alcohol, as the hydrogen donor, on the efficiency and selectivity of the asymmetrictransferhydrogenation (ATH) of imines is reported for the first time. This discovery not only leads to a highly enantioselective access to N‐aryl and N‐alkyl amines, but also provides new insight into the mechanism of the ATH of imines. Both experimental and computational studies provide support