Photocycloaddition of N-4-alkenyl substituted unsaturated imides

Tetrahedron Letters

Volumn 39, Issue 40, 1998, Pages 7423-7426

  Booker Milburn, Kevin I ^a   Costin, Nicola J ^a   Dainty, Richard F ^a   Patel, Dhiren ^a   Sharpe, Andrew ^a  

^a UNIVERSITY OF EAST ANGLIA   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

1 AZABICYCLO[5.3.0]DEC 3 ENE; ALKENYL GROUP; BICYCLO COMPOUND; IMIDE; MALEIMIDE DERIVATIVE; UNCLASSIFIED DRUG;

ARTICLE; CYCLIZATION; MOLECULAR DYNAMICS; STEREOCHEMISTRY; ULTRAVIOLET IRRADIATION;

EID: 0032192167     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)01613-X     Document Type: Article

References (13)

1. 1. (a) Booker-Milburn, K.I.; Cowell, J.K.; Sharpe, A.; Delgado Jiménez, F. Chem.Commun. 1996, 249;
2. (b) Booker-Milburn, K.I.; Gulten, S.; Sharpe, A. Chem. Commun. 1997, 1385.
3. 2. Mazzocchi, P.H.; Bowen, M.; Narain, N. J.Am.Chem. Soc. 1977, 99, 7063.
4. 3. (a) Mazzocchi, P.M.; Khachik, F.; Wilson, P. J.Am.Chem. Soc. 1981, 103, 6498.;
5. (b) Mazzocchi, P.H.; Wilson, P.; Khachik, F.; Klingler, L.; Minamikana, S. J.Org.Chem. 1983, 48, 2981;
6. (c) Mazzocchi, P.H.; Minamikana, S.; Wilson, P.; Bowen, M.; Narain, N. J.Org.Chem. 1981, 46, 4846.
7. 4. Although MS and spectral data suggested the [2+2] dimer was formed, rigourous structural assignment was not possible due to the fact that the product was obtained as a complex mixture of stereoisomers.
8. +) amu.
9. 6 Konzelman, L.M.; Conley, R.T. J.Org.Chem. 1968, 33, 3828.
10. 7. For example cycloadduct 18 exhibited the following nOe enhancements. (equation presented)
11. 8. Although the mechanism is not known with certainty it can be postulated from the work of Mazzocchi (Ref. 3) that the reaction proceeds via direct [2+2] cycloaddition to the zwitterionic tricyclic species 24 followed by fragmentation to the product. The stereochemistry observed with the cyclic alkenes used in this study would support the Mazzocchi mechanism. These cycloadditions must be remarkably fast, given that we have found that the intermolecular [2+2] photocycloaddition of the maleimide alkene with other alkenes is a very facile and efficient process (Ref. 1). Although it is probably mechanistically incorrect we have found it useful, for retrosynthetic purposes, to consider this reaction as a diradical [5+2] cycloaddition as illustrated below. (equation presented)
12. 9. Iida, H.; Takarai, T.; Kibayashi, C. J.Org.Chem. 1978, 43, 975.
13. 10. Hartmann, J.; Schlosser, M. Helv. Chim. Acta 1976, 59, 453.