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Synthesis of spirocyclic azacycles from the cyclization of furan tethered N-acyliminium ions

Journal Article


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Abstract


  • The protic and Lewis acid promoted cyclization reactions of tethered furan-4,5-dihydroxypiperid-2-ones, furan-4,5-diacetoxypiperid-2-ones and furan-3,4-diacetoxypyrrolid-2-ones, via their corresponding N-acyliminium ion intermediates, have been studied. In the case of the furan-4,5-dihydroxypiperid-2-one 2a and its diacetate derivative 2b, macrocyclic products were formed from an initial intermolecular reaction between 2a or 2b, via the nucleophilic C5 furan carbon, and their corresponding N-acyliminium ion intermediates. When the furan C5 position of 2b was blocked by substitution with bromine then TFA or Sc(OTf)3 catalysed cyclization reactions gave a spirotricyclic product (a 5-6-6-tricycle) in a highly diastereoselective manner. Cyclization of the analogous C5-Br-furan-pyrrolidone 29 with TFA resulted in a related spirotricyclic (a 5-6-5 tricycle) product. Attempts to prepare an analogous azepine system, a 5-7-5 tricycle, were not successful. Cyclization reactions of the C5-PhS-furan- or C5-phenylsulfonyl-pyrrolidone analogues of 29 with TFA were also not successful.

UOW Authors


  •   Shengule, Sudhir R. (external author)
  •   Willis, Anthony C. (external author)
  •   Pyne, Stephen

Publication Date


  • 2012

Citation


  • Shengule, S. R., Willis, A. & Pyne, S. G. (2012). Synthesis of spirocyclic azacycles from the cyclization of furan tethered N-acyliminium ions. Tetrahedron, 68 (4), 1207-1215.

Scopus Eid


  • 2-s2.0-84855457893

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1081&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/82

Has Global Citation Frequency


Number Of Pages


  • 8

Start Page


  • 1207

End Page


  • 1215

Volume


  • 68

Issue


  • 4

Place Of Publication


  • United Kingdom

Abstract


  • The protic and Lewis acid promoted cyclization reactions of tethered furan-4,5-dihydroxypiperid-2-ones, furan-4,5-diacetoxypiperid-2-ones and furan-3,4-diacetoxypyrrolid-2-ones, via their corresponding N-acyliminium ion intermediates, have been studied. In the case of the furan-4,5-dihydroxypiperid-2-one 2a and its diacetate derivative 2b, macrocyclic products were formed from an initial intermolecular reaction between 2a or 2b, via the nucleophilic C5 furan carbon, and their corresponding N-acyliminium ion intermediates. When the furan C5 position of 2b was blocked by substitution with bromine then TFA or Sc(OTf)3 catalysed cyclization reactions gave a spirotricyclic product (a 5-6-6-tricycle) in a highly diastereoselective manner. Cyclization of the analogous C5-Br-furan-pyrrolidone 29 with TFA resulted in a related spirotricyclic (a 5-6-5 tricycle) product. Attempts to prepare an analogous azepine system, a 5-7-5 tricycle, were not successful. Cyclization reactions of the C5-PhS-furan- or C5-phenylsulfonyl-pyrrolidone analogues of 29 with TFA were also not successful.

UOW Authors


  •   Shengule, Sudhir R. (external author)
  •   Willis, Anthony C. (external author)
  •   Pyne, Stephen

Publication Date


  • 2012

Citation


  • Shengule, S. R., Willis, A. & Pyne, S. G. (2012). Synthesis of spirocyclic azacycles from the cyclization of furan tethered N-acyliminium ions. Tetrahedron, 68 (4), 1207-1215.

Scopus Eid


  • 2-s2.0-84855457893

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1081&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/82

Has Global Citation Frequency


Number Of Pages


  • 8

Start Page


  • 1207

End Page


  • 1215

Volume


  • 68

Issue


  • 4

Place Of Publication


  • United Kingdom