Asymmetric induction in the solid state photochemistry of an α- mesitylacetophenone derivative through the use of ionic chiral auxiliaries

Tetrahedron Letters

Volumn 40, Issue 50, 1999, Pages 8733-8736

  Cheung, Eugene ^a   Rademacher, Katja ^a   Scheffer, John R ^a   Trotter, James ^a  

^a UNIVERSITY OF BRITISH COLUMBIA   (Canada)

Author keywords

Asymmetric induction; Ketones; Photochemistry; Rearrangements

Indexed keywords

ACETOPHENONE DERIVATIVE; ALPHA MESITYLACETOPHENONE DERIVATIVE; AMINE; INORGANIC SALT; UNCLASSIFIED DRUG;

ARTICLE; CHIRALITY; CRYSTAL STRUCTURE; ENANTIOMER; IRRADIATION; MOLECULAR MODEL; PHOTOCHEMISTRY; REACTION ANALYSIS; SYNTHESIS; X RAY CRYSTALLOGRAPHY;

EID: 0033544808     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)01867-5     Document Type: Article

References (12)

1. (a) Cheung, E.; Netherton, M. R.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc. 1999, 121, 2919;
2. (b) Leibovitch, M.; Olovsson, G.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc. 1998, 720, 12755;
3. (c) Gamlin, J. N.; Jones, R.; Leibovitch, M.; Patrick, B.; Scheffer, J. R.; Trotter, J. Acc. Chem. Res. 1996, 29, 203.
4. (a) Wagner, P. J.; Meador, M. A.; Zhou, B.; Park, B.-S. J. Am. Chem. Soc. 1991, 113, 9630;
5. (b) For a review on δ-hydrogen atom abstraction reactions, see: Wagner, P. J.; Park, B.-S. In Organic Photochemistry; Padwa, A., Ed.; Marcel Dekker: New York, 1991; Vol. 11, p. 227.
6. Carboxylic acid 1b was prepared from reaction of α-mesitylacetyl chloride with p-fluorophenylmagnesium bromide followed by treatment with sodium cyanide and hydrolysis. All new compounds described in the present paper gave spectroscopic data and elemental analyses completely in accord with their assigned structures. Details will be provided in a subsequent full paper.
7. 1; a=7.182(1) Å, b=6.048(1) Å, c=27.779(2) Å; β=97.094(9)°; Z=2; R=4.4%. Salt 1f: C2; a=17.732(5) Å, b=5.612(2) Å, c=25.720(4) Å; β=109.18(2)°; Z=4; R=4.5%. Salt 1g: P1; a=10.519(3) Å, b=13.927(5) Å, c=9.501(3) Å; α=99.57(3)°, β=114.97(2)°, γ=101.68(3)°; Z=2; R=6.3%; two independent molecules in the asymmetric unit.
8. Since the absolute configuration of the chiral auxiliary of salt 1e is known, the absolute conformation of the α-mesitylacetophenone moiety is established unequivocally.
9. For a discussion of the distance and angular requirements in Norrish/Yang type II hydrogen atom abstraction reactions, see: Ihmels, H.; Scheffer, J. R. Tetrahedron 1999, 55, 885 and references cited therein.
10. Absolute configuration studies aimed at verifying this prediction are planned. Formation of the (R)-enantiomer would require an approximately 180° rotation of the acyl group, which is topochemically unlikely in the crystalline state.
11. For additional examples of salts that give low ees owing to the presence of independent, mirror-image related conformers in the asymmetric unit, see the preceding paper in this issue as well as: (a) Jones, R.; Scheffer, J. R.; Trotter, J.; Yang, J. Tetrahedron Lett. 1992, 33, 5481;
12. (b) Jones, R.; Scheffer, J. R.; Trotter, J.; Yang, J. Acta Crystallogr. 1994, B50, 601.