A series of dibenzo [n.2.2] bicyclic compounds (n = 2-20) were prepared in one step and good yields starting from dimethyl anthracene-9,10-dicarboxylate. Reduction of the aromatic diester using lithium/naphthalene led to a bis-enolate that was cyclized with a variety of bis-electrophiles. The ease of the cyclization is probably due to the puckered conformation of the intermediate formed after the first alkylation step, in which the newly introduced chain that will become the bridge portion occupies a pseudoaxial position, positioning the leaving group close to the enolate nucleophile in the macrocyclization step.
A one-pot, enantioselective strategy for the dearomatizationannulation of aromatic diesters to give a range of highly functionalized polycyclic molecules with excellent enantioselectivity is presented. This methodology is based on the reaction of bisenolates, prepared by treating aromatic diesters with trialkyltin lithium reagents, which involves a stanna-Brook rearrangement, with 1,ω-dihaloalkanes and
A One-Step, Versatile Synthesis of Dibenzo [n.2.2] Macrobicyclic Compounds via a Conformation-Directed Macrocyclization Reaction. -A highly efficient synthesis of bridged bicyclic compounds based on reductive alkyltin of anthracene dicarboxylate (I) is presented. Reduction of the aromatic diester using lithium and naphthalene leads to an intermediate bis-enolate which is subsequently cyclized with a variety of bis-electrophiles. The new method allows easy access to medium-and large-sized dibenzobicycles. -(LOBATO, R.; VEIGA, A. X.; PEREZ-VAZQUEZ, J.; FERNANDEZ-NIETO, F.; PALEO*, M. R.; SARDINA, F. J.; Org. Lett. 15 (2013) 16, 4090-4093, http://dx.
The process is applied to the synthesis of the tricyclic benzofuran derivative (XIX), a valuable intermediate in the synthesis of galantamine alkaloid acting as a selective acetylcholinesterase inhibitor.
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