摘要:
The asymmetric syntheses of two key intermediates, 8 and 15, in >99% ee are reported. These compounds are prepared by diastereofacial addition of lithiodimethylphenylsilane to chiral naphthyloxazolines followed by methyl iodide trapping. The two stereocenters are formed in greater than 95% ds, and the silyl center is subsequently removed to give the 1,1-disubstituted tetralins 8, 9, or 12. These chiral substances are readily transformed into the titled compounds as described in the literature. The absolute configuration of these intermediates has been confirmed by X-ray analysis and corrects an earlier misassignment.