Highly stereoselective addition of alkylcopper reagents to n-acyliminium ions. Enantioselective synthesis of trans-2- butyl-5-heptylpyrrolidine.

✍ Scribed by Marco Skrinjar; Lars-G. Wistrand

• Book ID: 104222146
• Publisher: Elsevier Science
• Year: 1990
• Tongue: French
• Weight: 211 KB
• Volume: 31
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)88878-4

✦ Synopsis

Summarv. Addition of RCu, BFs to the electrochemically prepared a-methoxy proline ester 1 has been shown to be highly truns (296 %) selective. This reaction has been developed into an enantioselective synthesis of the ant trail feromone trans-2-butyl-S-heptyylpyrrolidine.

Nucleophilic additions to N-acyliminium ions have been shown to have great synthetic potential'. In particular, recent applications to the enantioselective synthesis of various nitrogencontaining natural products have been succesful*. In 1986, Shono and coworkers reported a highly stereoselective amidoalkylation of a 6-methoxy-pipecolic acid derivatives. However, analogous substitutions on the proline derivative 1 gave mixtures of isomers (cis trans -7:3):

. Similar results were reported by Malmberg and Nyber& for the corresponding N-formyl derivative.

We recently reported5 on the facile cleavage of N-acylated cyclic N,O-acetals (prepared by anodic methoxylation of the corresponding amide or carbamate6) with RCu, BF3 yielding the corresponding a-alkylated amide or carbamate. We now report on the highly steresoelective