Aldol condensation acetoacetate dianion

Michael addition of the dianions derived from -dicarbonyl compounds facilitated yet another annulation - Michael addition of a dianion then intramolecular aldol condensation (Scheme 6.89) [112]. Complexation of ATPH with trans-chal-cone (112) in CH2CI2 at -78 °C, followed by treatment with the dianion of methyl acetoacetate gave, after quenching with aqueous HCl, bicyclic product 113 in a nearly quantitative yield. This system can be used for elaboration of the bicyclo [3,5,l]undecane ring system in 114, as can be found in the backbones of terpenoids and the taxol family. 

One of the most complex molecules yet prepared by these biomimetic approaches is the x-etetramid (158 Scheme 7). The 3-pyrrolidinoglutaric acid diamide (153) is condensed with two equivalents of the dianion of r-butyl acetoacetate. The putative intermediate (154) undergoes spontaneous cyclization to provide the naphth ene derivative (155). This substance is transformed by a sequence of steps into naph-thalenopyrone (156), which is extended by reaction with an isoxazole dianion. Spontaneous aldolization again occurs, yielding the anthracene derivative (157). Closure of the final ring ensues when (157) is treated with HI. 

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