Sn(IV) porphyrins as NMR shift reagents and supramolecular protecting groups: Preparation of a carboxylate-catenane porphyrin complex

Organic Letters

Volumn 1, Issue 9, 1999, Pages 1343-1346

  Tong, Yin ^a   Hamilton, Darren G ^a   Meillon, Jean Christophe ^a   Sanders, Jeremy K M ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000086128     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol990891j     Document Type: Article

References (14)

1. Arnold, D. P.; Morrison, E. A.; Hanna, J. V. Polyhedron 1990, 9, 1331-1336.
2. Smith, G.; Arnold, D. P.; Kennard, C. H. L.; Mak, T. C. W. Polyhedron 1991, 10, 509-516.
3. Hawley, J. C.; Bampos, N.; Abraham, R. J.; Sanders, J. K. M. Chem. Commun. 1998, 661-662.
4. Zhang, Q.; Hamilton, D. G.; Feeder, N.; Teat, S. J.; Goodman, J. M.; Sanders, J. K. M. New J. Chem, 1999, 23, 897-903.
5. Menzer, S.; White, A. J. P.; Williams, D. J.; Belohradsky, M.; Shipway, A. N.; Stoddart, J. F. Macromolecules 1998, 31, 295-307.
6. Hamilton, D. G.; Davies, J. E.; Prodi, L.; Sanders, J. K. M. Chem. Eur. J. 1998, 4, 608-620.
7. We suspect that the diimide macrocycle is susceptible to nucleophilic cleavage at sites adjacent to imide nitrogen since only the carboxylic acid crown 4 can be isolated from the attempted hydrolyses. A reagent that specifically attacks the methyl carbon of the ester group, for example a thiolate anion, may avoid this problem and effect the desired cleavage.
8. 3) and had identical spectroscopic properties to those reported in ref 5.
9. 1H NMR spectra. However, the complexed carboxylates were insensitive to the presence, or absence, of a bound group on the other porphyrin face, thus simplifying assignment of their resonances. In contrast, the porphyrin spectrum is sensitive to the number of axial substituents. In particular monosubstituted complexes lose the plane of the porphyrin system as a symmetry element and as a consequence those regions of the spectrum containing porphyrin resonances greatly increase in complexity if a significant amount of such a species is present. The number and relative amounts of the complex species can be most conveniently followed by examination of the meso region of the spectrum (10-11 ppm) and by examining the first methylene group of the propionate side chains of the porphyrin (≈ 4.5 ppm). The protons of the latter are diastereotopic in monosubstituted complexes where the two faces of the porphyrin are inequivalent.
10. 3, 93:7). The protocol for reactions conducted in the absence of porphyrins was identical in all respects save for the omission of the Sn(IV) porphyrin.
11. Houk, K. N.; Menzer, S.; Newton, S. P.; Raymo, F. M.; Stoddart, J. F.; Williams, D. J. J. Am. Chem. Soc. 1999, 121, 1479-1487.
12. 3. It is therefore improbable, especially in a competitive hydrogen-bonding solvent such as DMF, that a conformational constraint imposed by carboxylic acid dimer formation is responsible for the poor yield of 1 obtained from the free crown.
13. Hamilton, D. G.; Sanders, J. K. M. Chem. Commun. 1998, 1749-1750.
14. Kidd, T. J.; Leigh, D. A.; Wilson, A. J. J. Am. Chem. Soc. 1999, 121, 1599-1600.