Intramolecular 3+21 cycloaddition Claisen condensations

Dieckmann condensation Intramolecular Claisen condensation, producing cyclic 3-keto esters. Diels-Alder reaction Concerted (4 + 2) cycloaddition of dienes, with four it electrons, and alkenes, with... 

More recently (2004), Joule proposed a novel synthetic route to access the akuammiline scaffold with reports from his group s synthetic efforts toward realizing this plan. Retrosynthetically, they envisioned akuammiline (1) to result from late stage imine formation of ketone 247 (Scheme 32). The functionality at position 16 would then be elaborated from a carbonyl contained in diketone 248, which in turn was planned to be obtained via an intramolecular Claisen condensation and double bond isomerization of enamine 249, the latter the product of an aza-Diels—Alder cycloaddition involving cyclic 1-aza-1,3-diene 250 and an acrylate 251. To access azadiene 250 they planned an oxidative ring opening of bicyclic pyrrole 252. 

MM has been used to study the transition states involved in Sa/2 reactions, hydrob-orations, cycloadditions (mainly the Diels-Alder reaction), the Cope and Claisen rearrangements, hydrogen transfer, esterification, nucleophilic addition to carbonyl groups and electrophilic C/C bonds, radical addition to alkenes, aldol condensations, and various intramolecular reactions [24],... 

---