The Intramolecular Cycloaddition Of 2-azaallyl Anions.

We have prepared the perhydrocyclopenta b pyrrole and perhydroindole ring systems by the intramolecular cycloaddition of 2-azaallyl anions with both alkyl and phenyl substituted olefins. Thus, N-benzylidene-5-hexen-1-amine 1 was treated in tetrahydrofuran at room temperature with 1.5 equivalents of lithium diisopropylamide to give 2-phenyl-octahydrocyclopenta b pyrrole as a mixture of isomers. In like fashion N-benzylidene-1-phenyl-5-hexen-1-amine gave 1,6a-diphenyloctahydro-(2(alpha),3a(beta))-cyclopenta b pyrrole, N-(diphenylmethylene)-5-hexen-1-amine gave 2,2-diphenyl-octahydro-(3a(beta),6a(beta))-cyclopenta b pyrrole, N-(p-methoxy-benzylidene)-5-hexen-1-amine gave 2-(p-methoxyphenyl)-octahydrocyclopenta b pyrrole as a mixture of isomers, N-benzylidene-6-hepten-1-amine gave 2-phenyloctahydroindole as a mixture of isomers, N-benzylidene-5-phenyl-5-hexen-1-amine gave 2,3a-diphenyloctahydrocyclopenta b pyrrole as a mixture of isomers, and N-benzylidene-6-phenyl-6-hepten-1-amine gave 2,3a-diphenyloctahydroindole as a mixture of isomers. The cycloaddition of 1 was observed to proceed through the regioisomeric imidazolidines 2,4-diphenyl-3-hexenyl-5-pentenyl-imidazolidine and 4,5-diphenyl-3-hexenyl-2-pentenyl-imidazolidine via an intermolecular cycloaddition-cycloreversion. Other imidazolidines were observed to undergo this same anionic cycloreversion process. Thus, 4,5-diphenyl-3-hexyl-2-pentenyl-imidazolidine was treated with lithium diisopropylamide to give, after cycloreversion of the metallated imidazolidine to the 2-azaallyl anion and intramolecular cycloaddition, 2-phenylperhydrocyclopenta- b pyrrole as a mixture of isomers. We have shown that imidazolidines are effective precursors for 2-azaallyl anions which can be trapped with olefins either inter- or intramolecularly. This new methodology promises to greatly expand the synthetic utility of 2-azaallyl anions. Additionally, the intramolecular cycloaddition of 2-azaallyl anions described above may prove applicable to the synthesis of natural products which contain the perhydrocyclopenta b pyrrole or perhydroindole ring systems.Ph.D.Organic chemistryPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127935/2/8621399.pd