Controlled Synthesis of Cis or Trans Isomers of 1,3-Disubstituted Tetrahydroisoquinolines and 2,5-Disubstituted Pyrrolidines

The stereoselective outcome of Pd(II)- or Ag(I)-catalyzed intramolecular N-alkylation to afford 1,3-disubstituted 1,2,3,4-tetrahydroisoquinolines was examined. In the absence of additional substituents, Pd(II) allows a facile access to the cis isomers, while Ag(I) favors formation of the trans
isomers. The same observation was made for the synthesis of 2,5-disubstituted pyrrolidines. Possible
reasons for the observed stereoselectivities are discussed.