Asymmetric synthesis of piperidines and octahydroindolizines using a one-pot ring-closure/N-debenzylation procedure
摘要:
The conjugate addition of an enantiopure lithium amide to a zeta-hydroxy-alpha,beta-unsaturated ester followed by a one-pot ring-closure/N-debenzylation protocol has been used in the asymmetric syntheses of (S)coniine and (R)-delta-coniceine (isolated as the corresponding hydrochloride salts), and (R,R)-1-(hydroxymethyl)octahydroindolizine (the bicyclic fragment of stellettamides A-C). (C) 2011 Elsevier Ltd. All rights reserved.
The Hancock Alkaloids (−)-Cuspareine, (−)-Galipinine, (−)-Galipeine, and (−)-Angustureine: Asymmetric Syntheses and Corrected <sup>1</sup>H and <sup>13</sup>C NMR Data
作者:Stephen G. Davies、Ai M. Fletcher、Ian T. T. Houlsby、Paul M. Roberts、James E. Thomson、David Zimmer
DOI:10.1021/acs.jnatprod.8b00672
日期:2018.12.28
(-)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-( o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR data for the originally isolated samples of (-)-cuspareine, (-)-galipinine, and (-)-angustureine are also reported, representing a valuable reference resource for these popular synthetic
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 %)
A series of chiral cyclometalated iridiumcomplexes have been synthesised by cyclometalating chiral 2-aryl-oxazoline and imidazoline ligands with [Cp*IrCl2]2. These iridacycles were studied for asymmetric transfer hydrogenation reactions with formic acid as the hydrogen source and were found to display various activities and enantioselectivities, with the most effective ones affording up to 63% ee
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.