Tricyclic 3-pyrrolin-2-ones

Recently, Jia, Li and coworkers have investigated multicomponent reactions that lead to the formation of tricyclic 3-pyrrolin-2-ones (Scheme 77 20140L5604). Heating tropone (306), the aUene 307, and isopropyl... 

Boiadjiev and Lightner synthesized fluorescent tricyclic-bridged pyrrinones such as 31 by base-catalyzed condensation-cyclization of pyrrolin-2-one 112 with pyrrole aldehyde 113 (Equation 24) <2005M553, 2005JOC689>. 

In addition to the two asymmetric syntheses above described, two racemic syntheses of tetraponerines based on the 5=6-5 tricyclic skeleton have been published. Thus, Plehiers et al. [199] have reported a short and practical synthesis of ( )-decahydro-5Tf-dipyrrolo[l,2-a r,2/-c]pyrimidine-5-carbonitrile (238), a pivotal intermediate in the synthesis of racemic tetraponerines-1, -2, -5 and -6, in three steps and 24% overall yield from simple and inexpensive starting materials. The key reaction of the synthesis was a one-pot stereoselective multistep process, whereupon two molecules of A pyrroline react with diethylmalonate to afford the tricyclic lactam ester 239, possessing the 5-6-5 skeleton (Scheme 10). Hydrolysis of the carboethoxy group of 239 followed by decarboxylation yielded lactam 240, that was converted into a-aminonitrile 238 identical in all respects with the pivotal intermediate described by Yue et al. [200] in their tetraponerine synthesis. 

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