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Synlett 2008(7): 1036-1038
DOI: 10.1055/s-2008-1072658
DOI: 10.1055/s-2008-1072658
LETTER
© Georg Thieme Verlag Stuttgart · New York
Novel Use of N-Carboalkoxy α,β-Unsaturated Iminium Ions as Dienophiles in Diels-Alder Reactions
Further Information
Received
1 February 2008
Publication Date:
28 March 2008 (online)
Publication History
Publication Date:
28 March 2008 (online)
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Abstract
Tricyclic spiro-N,O-acetals have been assembled in a single step by cycloaddition of hydroxymethyl-substituted dienes to iminium ion activated dienophiles that were generated by acidolysis of α,β-unsaturated-N-carboalkoxy-N,O-acetals or β-methoxymethyl-N-carboalkoxy-enamines. The cycloaddition was conducted using Sc(OTf)3 as a mild Lewis acid affording the endo adducts in moderate yields.
Key words
iminium ion - Diels-Alder - cycloaddition
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References and Notes
The anti-methine endo adducts were identified as the lowest energy conformers on the basis of B3LYP/6-311G(d)optimization and frequency calculations which were performed using Chem3D®.