Preparation of a Phosphorus Ylid from 1,3-Dithiolan-2-yltriphenylphosphonium Fluoroborate and its Application to KeteneS,S-Acetal Synthesis

An asymmetric synthesis of (+)-morphinans in high enantiomeric purity

“…JV-Benzyl-5,6,7,8-tetrahydroisoquinolinium Bromide (8). A solution of 10.0 g (7.7 mmol) of distilled isoquinoline in 67 mL of trifluoroacetic acid containing 5.0 g of 57c palladium on carbon was hydrogenated in the manner of Eliel and Vierhapper8 at 50 psi of H2, 50 °C over 48 h. The catalyst was removed by filtration, and the reaction mixture was carefully neutralized with solid KOH and 20 7o KOH solution.…”

“…For a detailed discussion on the Grewe cyclization, see ref 5b above. (8) Vierhapper, F. W.; Eliel, E. L. J. Org. Chem.…”