High kinetic resolution in the addition of a racemic allenylzinc onto enantiopure N-tert-butanesulfinimines: concise synthesis of enantiopure trans-2-ethynylaziridines.
Enantiopure trans-ethynyl N-tert-butanesulfinylaziridines (R(S))-6 were prepared in good to excellent yields by the condensation of the racemic allenylzinc species 1 derived from 3-chloro-1-trimethylsilylpropyne onto the corresponding enantiopure N-tert-butanesulfinimines (R(S))-5. The absolute stereochemistry of enantiopure N-tert-butanesulfinylaziridines (R(S))-6 was shown to be (R(S),2R,3R) and results from a chelate-type transition state in which the zinc atom of allenylzinc 1 is coordinated by both the nitogen and the oxygen atoms of the imine. Further removal of the N-tert-butanesulfinyl auxiliary of alkyl 3-substituted and 3,3-disubstituted ethynyl N-tert-butanesulfinylaziridines (R(S))-6 could be achieved by treatment with HCl in MeOH affording the corresponding deprotected aziridines (2R,3R)-9 and (2R)-9 respectively as enantiomerically pure compounds.
Chemla
Fabrice
F
UMR 7611, Laboratoire de Chimie Organique, Université Pierre et Marie Curie, Tour 44-45, Case 183, 4 Place Jussieu, 75252 Paris Cedex 05, France.
Ferreira
Franck
F
D000466:Alkadienes / Q000737:chemistry*; D001388:Aziridines / Q000138:chemical synthesis*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
D000466:Alkadienes; D001388:Aziridines; D009942:Organometallic Compounds; D015032:Zinc