ISSN:
1434-193X
Keywords:
C-C coupling
;
α-Cyanoamines
;
Electrochemistry
;
Iminium cation
;
α-Silylamines
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The electrochemical cyanation of N-benzyl-substituted cyclic six-membered α-silylamines including tetrahydroquinoline and piperidine derivatives was studied. The results of these investigations demonstrate that α-silylamines are valuable precursors for the preparation of the corresponding α-cyanoamines. The TMS group α to the N atom not only governs the chemoselectivity of the iminium formation through a preferential desilylation reaction under the experimental conditions (i.e., amine cation radical desilylation versus deprotonation), it also lowers the oxidation potential of tertiary amines compared to their non-TMS counterparts. Both the stereoselectivity and regioselectivity of the cyanide addition were investigated with 3-methylpiperidine as the model compound. The formation of a single cisdiastereoisomer in which the 2-cyano group is axial and the 5-methyl group is equatorial, indicates that the addition of the cyanide anion onto the iminium species is under stereoelectronic control. In addition, the redox reaction involving the intermediate nitrogen-centered cation radical and the cyanide anions played no role, because the α-silyl radical has such a short lifetime.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
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