Darstellung und Verhalten von 1.5‐Didehydro‐hygrin und N ‐Methyl‐1.6‐didehydro‐isopelletierin

Abstract

Es wird iiber eine einstufige Synthese der als Alkaloidvorstufen diskutierten Titelverbindungen berichtet und ihre Cyclisierung zu Tropinon und Pseudopelletierin nachgewiesen. Ferner wird eine iiber die I-Methyl-~1-pyrrolinium-carbonsaure-(5) (19) fuhrende, mehrstufige Synthese von I .5-Didehydro-hygrin (5) beschrieben.Preparation and Behaviour of 1.5-Didehydrohygrine and N-Methyl-1.6-didehydroisopelletierine A one step synthesis of the title compounds and their cyclisation to tropinone and pseudopelletierine is reported. A second synthesis of I .5-didehydrohygrine (5) involving I-Methyl-A1-pyrrolinium-5-carboxylic acid (19) is described. HessJahrg. 105

Heterocyclic Compounds in Alkaloid Synthesis

“…The first synthesis of hygrine (Hess, 1913), a minor alkaloid of the Peruvian coca shrub, is based on the early availability of pyrrole and the knowledge that its Grignard reagent undergoes predominantly 2-substitution with electrophihc reagents (E + ) (Scheme 15) (Gossauer, 1974). Thus the required 3-carbon unit was appended with propylene oxide to give the alcohol 1 together with a minor amount of an isomeric alcohol presumably resulting from alternate attack on propylene oxide.…”