Diastereoselective addition of organometallic reagents to chiral iminium ions: synthesis of (S)-(+)-cryptostyline I.
Richard P. Polniaszek and Lawrence W. Dillard. Tetrahedron Letters, Vol. 31, No 6, pp. 797-800, 1990
We are interested in determining the factors which influence the sense and extent of stereoselection associated with the addition of various nucleophiles to iminium ions. Previous publications from these laboratories have revealed that iminium ions undergo highly stereoselective hydride reduction with NaBH4 in methanol to afford (1S)-1,2-disubstituted-1,2,3,4-tetrahydroisoquinolines. This letter describes complementary experiments involving nucleophilic addition of organometallic reagents to iminium ions.