Highly stereoselective benzylation of N-sulfinylketimines.
The benzylation of N-sulfinyl ketimines with 2-(p-tolylsulfinyl)ethylbenzene and LDA afford t-alkylamines in good yields. The configuration at each one of the new chiral centers simultaneously created in this reaction is controlled by the configuration of the sulfinyl groups at the nucleophile and electrophile, respectively. Thus, the reactions of the (S)-sulfoxide 6 with the N-(S)-sulfinylketimines 3 only yield the anti diastereoisomers 18, whereas the syn diastereoisomers 19 are exclusively formed in reactions of (S)-6 with N-(R)-sulfinylketimines 3. After a two-step desulfinylation process ((i) TFA, (ii) Ra-Ni), this reaction provides a procedure for synthesizing any epimer of alpha,alpha-dibranched beta-alkylarylamines in optically pure form by choosing the configuration of the starting materials. A similar behavior is observed for carbanions derived from the O-protected 2-(p-tolylsulfinyl) benzyl alcohol 7 thus allowing the synthesis of the optically pure anti- and syn-1,2-amino alcohols containing a chiral quaternary carbon adjacent to the nitrogen.
García Ruano
José Luis
JL
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. joseluis.garcia.ruano@uam.es
Alemán
José
J
Parra
Alejandro
A
D000478:Alkylation; D007097:Imines / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D013457:Sulfur Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D007097:Imines; D013457:Sulfur Compounds