Co-reporter:Siobhan R. Smith;Dr. Charlene Fallan;Dr. James E. Taylor;Ross McLennan;Dr. David S. B. Daniels;Dr. Louis C. Morrill; Alexra M. Z. Slawin ; Andrew D. Smith
Chemistry - A European Journal 2015 Volume 21( Issue 29) pp:10530-10536
Publication Date(Web):
DOI:10.1002/chem.201501271
Abstract
A highly enantioselective Lewis base-catalysed formal [3+2] cycloaddition of ammonium enolates and oxaziridines to give stereodefined oxazolidin-4-ones in high yield is described. Employing an enantioenriched oxaziridine in this process leads to a matched/mis-matched effect with the isothiourea catalyst and allowed the synthesis of either syn- or anti-stereodefined oxazolidin-4-ones in high d.r., yield and ee. Additionally, the oxazolidin-4-one products have been derivatised to afford functionalised enantioenriched building blocks.
Co-reporter:Eoin Gould, Daniel M. Walden, Kevin Kasten, Ryne C. Johnston, Jiufeng Wu, Alexandra M. Z. Slawin, Thomas J. L. Mustard, Brittany Johnston, Tony Davies, Paul Ha-Yeon Cheong and Andrew D. Smith
Chemical Science 2014 vol. 5(Issue 9) pp:3651-3658
Publication Date(Web):03 Jul 2014
DOI:10.1039/C4SC00879K
The regiodivergent O- to C- or N-carboxyl transfer of pyrazolyl carbonates is described, with DMAP giving preferential N-carboxylation and triazolinylidenes promoting selective C-carboxylation (both with up to >99:1 regioselectivity). An enantioselective O- to C-carboxyl variant using NHC catalysis is demonstrated (up to 92% ee), while mechanistic and DFT studies outline the pathways operative in this system and provide insight into the reasons for the observed selectivity.
Co-reporter:Dorine Belmessieri;laHoupliere;Ewen D. D. Calder;Dr. James E. Taylor ; Andrew D. Smith
Chemistry - A European Journal 2014 Volume 20( Issue 31) pp:9762-9769
Publication Date(Web):
DOI:10.1002/chem.201402684
Abstract
A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)-(−)-tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r.syn/anti, 99 % eesyn), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti-diastereoisomers as the major product (up to 10:90 d.r.syn/anti, 99 % eeanti).
Co-reporter:Eoin Gould, Tomas Lebl, Alexandra M. Z. Slawin, Mark Reid, Tony Davies and Andrew D. Smith
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 45) pp:7877-7892
Publication Date(Web):16 Oct 2013
DOI:10.1039/C3OB41719K
Double asymmetric induction has been employed as a tool to optimise pyrazolidinone-derived organocatalysts for the asymmetric iminium ion catalysed Diels–Alder reaction. Mechanistic studies revealed a superior hydrazide catalyst deriving from methanolysis of the chiral pyrazolidinone precursor. This catalyst displays unusually high endo diastereoselectivity and good enantioselectivity with a range of β-arylenals and cyclic dienes at catalyst loadings as low as 1 mol%.
Co-reporter:Kenneth B. Ling and Andrew D. Smith
Chemical Communications 2011 vol. 47(Issue 1) pp:373-375
Publication Date(Web):23 Aug 2010
DOI:10.1039/C0CC02456B
α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates. Their ability to act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions is described.
Co-reporter:Kenneth B. Ling and Andrew D. Smith
Chemical Communications 2011 - vol. 47(Issue 1) pp:NaN375-375
Publication Date(Web):2010/08/23
DOI:10.1039/C0CC02456B
α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates. Their ability to act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions is described.
Co-reporter:Eoin Gould, Tomas Lebl, Alexandra M. Z. Slawin, Mark Reid, Tony Davies and Andrew D. Smith
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 45) pp:NaN7892-7892
Publication Date(Web):2013/10/16
DOI:10.1039/C3OB41719K
Double asymmetric induction has been employed as a tool to optimise pyrazolidinone-derived organocatalysts for the asymmetric iminium ion catalysed Diels–Alder reaction. Mechanistic studies revealed a superior hydrazide catalyst deriving from methanolysis of the chiral pyrazolidinone precursor. This catalyst displays unusually high endo diastereoselectivity and good enantioselectivity with a range of β-arylenals and cyclic dienes at catalyst loadings as low as 1 mol%.
Co-reporter:Eoin Gould, Daniel M. Walden, Kevin Kasten, Ryne C. Johnston, Jiufeng Wu, Alexandra M. Z. Slawin, Thomas J. L. Mustard, Brittany Johnston, Tony Davies, Paul Ha-Yeon Cheong and Andrew D. Smith
Chemical Science (2010-Present) 2014 - vol. 5(Issue 9) pp:NaN3658-3658
Publication Date(Web):2014/07/03
DOI:10.1039/C4SC00879K
The regiodivergent O- to C- or N-carboxyl transfer of pyrazolyl carbonates is described, with DMAP giving preferential N-carboxylation and triazolinylidenes promoting selective C-carboxylation (both with up to >99:1 regioselectivity). An enantioselective O- to C-carboxyl variant using NHC catalysis is demonstrated (up to 92% ee), while mechanistic and DFT studies outline the pathways operative in this system and provide insight into the reasons for the observed selectivity.
