An enantioselective access to 1-alkyl-1,2,3,4-tetrahydroisoquinolines. Application to a new synthesis of (-)-argemonine.
Potassium ferricyanide oxidation of salt 1 gave isoquinolinone 7 whose treatment with Grignard reagents resulted in a high-yield formation of substituted isoquinolinium salts 5. The selectivity of the reduction of these salts to give derivatives 6 has been studied. Particularly good selectivities (82-84%) were observed when R is a benzylic group. On the basis of these results, a practical and enantioselective synthesis of the natural alkaloid (-)-argemonine is presented.
Youte
Jean-Jacques
JJ
Institut de Chimie des Substances Naturelles, CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
Barbier
Denis
D
Al-Mourabit
Ali
A
Gnecco
Dino
D
Marazano
Christian
C