DIENE CYCLIZATION TOWARD CHIRAL ACYLIMINI UM IONS

The Grignard reaction of 10-bromo-7-methyldeca-2,6-diene (5) with a C- 2-symmetric chiral imide 1 gave a corresponding hydroxy lactam 6 in 67 % yield. Acid cyclization of 6 gave chiral carbocycles ? and 8 in 53 a nd 15% yields, respectively. The stereochemistry of 8 was deduced by t he NOE and CD spectra of the derived ketone 10. In a similar manner, t he acid cyclization of the hydroxy lactam 12, prepared from the bromid e 5 and a chiral imide 11, afforded a chiral carbocycle, which was pur ified as an acetate 13 in 27% yield. The stereochemistry of 13 was con firmed by correlating to that of 8.