Cis synthesis

The intermediate 1,5-dicarbonyl compounds of type 24 (Scheme 1) can be constructed not only on the basis of meta-alkoxy-substituted benzyl ketones (C4 + Ci synthesis, Section II,C), but also under definite conditions starting from aryl ketones (C2 + C3 synthesis). Thus, in a molecule of acylveratrole derivatives of type 79, the excess of 7r-electron density due to the presence of two ortho-methoxy groups allows such compounds to be involved in electrophilic substitutions with benzoin (73URP2 74KGS1575). 

Silyl migration can be used advantageously as in a disorazole Ci synthesis by Meyers. Treatment of the hydroxyl with NaH results in TBS migration with concomitant liberation of an aldehyde which then reacts with the Horner-Emmons reagent to form the unsaturated ester. "... 

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