A Simple and Efficient Synthetic Route to Chiral Isopavines. Synthesis of (−)-O-Methylthalisopavine and (−)-Amurensinine

The isopavinan alkaloids (−)- O -methylthalisopavine ( 7a ) and (−)-amurensinine ( 7d ) have been synthesized in good yield and high ee from the appropriate 1,2-diarylethylamine derivatives using optically active β-amino alcohols as chiral support. This synthetic route employs as key steps the alkylation reaction of the azomethine derivatives 2 with Grignard reagents 1 and a novel one-pot double-intramolecular cyclization of the adequately functionalized 1,2-diarylethylamines 5 to afford a series of optically active isopavines 6a−d and 7a−d .