Abstract EN:

In this work, we proposed new domino anionic transformations based on the reactivity of stabilized carbanions from 1,3-dicarbonyls. The study allowed the synthesis of fused polycyclic molecules which can be used in the formation of structures present in a large number of natural products. First, we have extended and generalized a new facile two-carbon ring expansion of cyclopentanones by a domino C-C-dialkylation/retro-Dieckmann for the flexible preparation of functionalized seven-membered rings. We have also developped a stereoselective C-O-cycloalkylation cascade leading to vinyl enol ethers which could be involved in a Claisen rearrangement to give highly functionalized bridged bicyclic systems. Both, the mechanism and the stereoselectivity have been studied by semiempirical calculations which are qualitatively in agreement with the experimental results. In a second time, we described a new γ-functionalization of β-ketoamides with aromatic, aliphatic and α,β-ethylenic aldehydes. Thus, we accedγeed to γ-arylidenes, γ-alkylidenes et γ-allylidenes β-ketoamides which constitute cyclic Nazarov analogues having a high synthetic value with their three consecutive reactive sites, both nucleophilic and electrophilic. . .