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Synlett 1995; 1995(11): 1119-1120
DOI: 10.1055/s-1995-5207
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Diastereoselective Intramolecular Cyclization through the Triphenylphosphine/Carbon Tetrachloride System: Synthesis of Saturated 1,4-Dihetero Seven-membered Cycloacetals

A. Espinosa* , M. A. Gallo, J. Campos, J. A. Gómez
  • *Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Granada, 18071 Granada, Spain
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Publication Date:
31 December 2000 (online)

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Several 4-hetero-6-hydroxyalkanal dimethyl acetals cyclize to methoxy-1,4-heteroxepanes and 7-methoxy-N-tosylperhydro-1,4-oxazepine under the neutral and mild conditions mediated by the triphenylphosphine/carbon tetrachloride system with high diastereoselectivity (hetero = O, S, NTs). The results are evidence of the formation of the seven-membered ion 19. Starting with 4-aza-6-hydroxy-4-methylhexanal dimethyl acetal and 6-hydroxy-4-oxahexanal ethylene acetal, under the same conditions, the corresponding 6-chloro analogues are obtained with good yields.

Intramolecular cyclization - Triphenylphosphine/carbon tetrachloride - Alkoxy-1,4-heteroxepanes - 4-hetero-6-hydroxyalkanal dialkyl acetals