Chem Pharm Bull (Tokyo)
November 2017
An enantioselective intermolecular Rauhut-Currier (RC) reaction of nitroalkenes with ethyl allenoate has been established with quinidine-derived β-isocupreidine. The present RC reaction afforded α-functionalized allenoates 3 in up to 94% yield with 59% enantiomeric excess (ee).
View Article and Find Full Text PDFThe first enantio- and diastereoselective Betti/intramolecular aza-Michael sequence carried out using a C-symmetric chiral trisimidazoline organocatalyst is reported. The reaction of phenols and N-tosylimines bearing a Michael acceptor moiety afforded densely functionalized 1,3-disubstituted isoindolines bearing two stereogenic centers as single diastereomers in high yields (≤93%) and excellent enantioselectivities (≤99.9%).
View Article and Find Full Text PDFMixing of acryloylchloride, dienone 2, N,N-diisopropylethylamine with chiral organocatalyst 5a, which could simultaneously act as Brønsted and Lewis base catalysts, led to a one-pot amidation/Rauhut-Currier sequence, affording α-methylidene-γ-lactams 4. Catalyst 5a could be recovered and reused by acid/base extraction without any loss of catalytic activity in the stepwise protocol.
View Article and Find Full Text PDFC3-Symmetric chiral trisimidazolines with m-chloroperbenzoic acid promoted the organocatalytic oxidation of N-sulfonyl ketimine. The present imidazoline catalysis produced oxaziridines bearing a tetrasubstituted carbon stereogenic center in high yields with up to 87% ee.
View Article and Find Full Text PDFAn enantio-, diastereo-, regio-, and chemoselective phosphine-catalyzed β,γ-umpolung domino reaction of allenic esters with dienones has been developed for the first time. The designed sequence, involving oxy-Michael and Rauhut-Currier reactions, produced highly functionalized tetrahydrobenzofuranones, bearing a chiral tetrasubstituted stereogenic center, in up to 96 % ee.
View Article and Find Full Text PDFA highly enantioselective aza-Morita-Baylis-Hillman (aza-MBH) reaction of isatin-derived ketimines with acrolein was established using β-isocupreidine (β-ICD) or α-isocupreine (α-ICPN) as a chiral acid-base organocatalyst. The present protocol readily furnished (S) or (R)-aza-MBH adducts with a chiral tetrasubstituted carbon stereogenic center in up to 98% ee.
View Article and Find Full Text PDFHighly E-selective all-carbon tetrasubstituted alkenes with a C(sp(3))-F unit have been synthesized through a dehydroxyfluorination of Morita-Baylis-Hillman (MBH) adducts which can be readily prepared from α,β-unsaturated carbonyl compounds and α-keto esters. A variety of subsequent transformations afforded monofluoromethyl substituted heterocycles in high yields.
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