Diastereoselectivity in the addition and cycloaddition reactions of a chiral ester of 2//-azirine-3-carboxyIic acid

Journal of the Chemical Society - Perkin Transactions 1

Volumn , Issue 11, 1999, Pages 1399-1401

  Jose Alves M ^a,b   Bickley, Jamie F ^a   Gilchrist, Thomas L ^a  

^a UNIVERSITY OF LIVERPOOL   (United Kingdom)

^b UNIVERSITY OF MINHO   (Portugal)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33746394129     PISSN: 0300922X     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (12)

1. M. J. Alves and T. L. Gilchrist, Tetrahedron Lett., 1998,39, 7579.
2. W. Oppolzer, C. CHapuis'and M. J. Kelly, Helv. Chim.Acta, 1983, 66,2358;
3. W. Oppolzer, Tetrahedron, 1987,43, 1969.
4. W. Oppolzer, C. Chapuis and G. Bernardinelli, Tetrahedron Lett., 1984,25,5885.
5. 2 was 0.1289 (all data). CCDC reference number 207/327. See http://www.rsc.org/suppdata/pl/1999/1399 for crystallographic files in .cif format.
6. M. J. Alves, T. L. Gilchrist and J. H. Sousa, J. Chem. Soc., Perkin Trans, l, 1999, 1305.
7. Crystal data for 7. C23H3,NjO4S2, M = 466.71, a = 10.5115(12), 6 = 11.468(3), c = 20.141(3) A,U= 2427.9(7) AJ, r= 213(2) K, Z-4, /;(Mo-Ka) = 0.206 mm"'; 13051 reflections measured, 3150 unique (Ä= 0. 0643). The final ir.R2 was 0.0812 (all data).
8. Calculations were performed by Dr D. L. Cooper (University of Liverpool). RHF calculations with a standard 6-31G basis were carried out in which the carbonyl carbon was forced coplanar with the heavy atoms of the ring and all other parameters were fully optimised for a given dihedral angle. The différence in energy of conformations with dihedral angle 0° and 180° is 3 kJ mol"1 and for conformations with dihedral angle 0° and 90° is 8 kJ mol"1.
9. Preliminary results indicate that both diastereoisomers are also formed with the corresponding azirine bearing a more bulky A'.A'-dicyclohexylsulfonamidomethyl side chain.
10. A referee has questioned this explanation and has suggested that reaction might occur more selectively through a higher energy s-cis conformation of the ester, in which the rotamer 2c would be preferred since it avoids interactions between the méthylène group of the azirine and the methine of the auxiliary. This is feasible, although the proportion of the s-m conformer of an ester is usually small at room temp. (K. B. Wiberg and K. E. Laidig, J. Am. Client. Soc., 1987,109, 5935).
11. We thank the referee for this suggestion. 10 D. Tanner, Angew. Client., Int. Ed. Engl, 1994, 33, 599;
12. H. M. I. Osborn and J. Sweeney, Tetrahedron: Asymmetry, 1997, 8, 1693.