The Diamino Analogues of Privileged Corey–Bakshi–Shibata and Jørgensen–Hayashi Catalysts: A Comparison of Their Performance

Abstract

α,α-Diarylprolinol derivatives are well-established families of organocatalysts that are widely used to promote diverse asymmetric reactions. The enantioinduction generated from these ligands is mainly due to the gem-diphenyl carbinol fragment. For this reason, the synthesis of diaza analogues seemed an evident and attractive issue to address in the development of alternative chiral ligands. Although the O→N substitution and subsequent derivatization at first glance looked simple, it was necessary to deal with various unexpected synthetic difficulties. It was established that suitable modifications of the side chain in the diaza analogues afford reaction yields and stereoselectivities that are comparable to those exhibited by the amino alcohol analogues. Nevertheless, various potential applications still remain undeveloped. 1 Introduction 2 Oxazaborolidines and Diazaborolidines in Borane-Mediated Reduction of Prochiral Ketones 3 Organocatalyzed Asymmetric Epoxidations 4 Assessing the Organocatalytic Capability of the α,α-Diphenylprolinol Diaza-Analogues through Benchmark Mannich and Michael Reactions

Stereoselective Synthesis of δ- and ε-Amino Ketone Derivatives from N-tert-Butanesulfinyl Aldimines and Functionalized Organolithium Compounds

“…High-resolution mass spectra (HRMS) were also carried out in the electron impact mode (EI) at 70 eV on an Agilent 7200 spectrometer equipped with a time of flight (TOF) analyzer and the samples were introduced through a direct insertion probe, or through an Agilent GC7890B. NMR spectra were recorded at 300 or 400 MHz for 1 H NMR and at 75 or 100 MHz for 13 C NMR with a Bruker AV300 Oxford or a Bruker AV400 spectrometers, Scheme 5. Synthesis of azepanes 13a from N-tert-butanesulfinyl amino ketone derivative 9a.…”

“…High-resolution mass spectra (HRMS) were also carried out in the electron impact mode (EI) at 70 eV on an Agilent 7200 spectrometer equipped with a time of flight (TOF) analyzer and the samples were introduced through a direct insertion probe, or through an Agilent GC7890B. NMR spectra were recorded at 300 or 400 MHz for 1 H NMR and at 75 or 100 MHz for 13 C NMR with a Bruker AV300 Oxford or a Bruker AV400 spectrometers, respectively, using CDCl 3 as solvent, and TMS as internal standard (0.00 ppm). The data are reported as: (s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet or unresolved, br s = broad signal, coupling constant(s) in Hz, integration).…”

“…The data are reported as: (s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet or unresolved, br s = broad signal, coupling constant(s) in Hz, integration). 13 C NMR spectra were recorded with 1 H-decoupling at 100 MHz and referenced to CDCl 3 at 77.16 ppm. DEPT-135 experiments were performed to assign CH, CH 2 and CH 3 .…”

“…5-Chloro-2-methoxypent-1-ene (2b). Following the general procedure, compound 2b was obtained from 5-chloropent-1-yne (1b) as a colorless liquid (99% conversion of 1b into 2b by GC-MS analysis): C 6 H 11 OCl; 1 H NMR (400 MHz, CDCl 3 ) δ 1.92-1.99 (m, 2H), 2.26 (dd, J = 7.8, 6.7 Hz, 2H), 3.53 (s, 3H), 3.52-3.57 (m, 2H), 3.90-3.93 (m, 2H); 13 6-Chloro-2-methoxyhex-1-ene (2c). Following the general procedure, compound 2c was obtained from 6-chlorohex-1-yne (1c) as a colorless liquid (99% conversion of 1c into 2c by GC-MS analysis): C 7 H 13 OCl; 1 H NMR (400 MHz, CDCl 3 ) δ 1.59-1.67 (m, 2H), 1.73-1.82 (m, 2H), 2.13 (t, J = 7.4 Hz, 2H), 3.53 (s, 3H), 3.52-3.56 (m, 2H) 3.86-3.89 (m, 2H); 13…”

“…These compounds usually require the presence of protecting groups of the amino or the carbonyl functionalities to avoid inter-and intramolecular undesired condensations. The preparation of α- [2] and β-amino [3][4][5][6][7][8][9][10][11][12][13] ketones have been extensively studied, and in many of the methodologies leading to these compounds, nucleophilic additions to chiral imines are involved. Among chiral imines, those derived from tert-butanesulfinamide are of special relevance and have been recurrently used in organic synthesis [14][15][16].…”