| Abstract
| - A versatile methodology for the nucleophilic formylation andcyanation of conjugated enones isreported. The procedure is based on the use of formaldehydedimethylhydrazone, which, acting asa neutral formyl anion equivalent, adds to preformedtrialkylsilyl−enone complexes. Both 4-(silyloxy)-3-enal hydrazones 3 or deprotected 4-oxo aldehydemonohydrazones 4 can be obtained asproducts depending on quenching conditions. In full analogy, anasymmetric version of the reactionusing chiral formaldehyde SAMP-hydrazone as a neutral synthon of thechiralformyl anion hasbeen developed, giving rise to the corresponding adducts 5and 6 in good yields and with excellentdiastereoselectivities (de 85−≥98%). Ozonolysis orHCl-mediated hydrolysis of adducts 4 and6readily affords racemic and optically enriched 4-oxo aldehydes7, respectively. Additionally, high-yielding MMPP-oxidative cleavage of 4-oxo hydrazones 4and 6 has been performed to obtain 4-oxonitriles 8 in racemic and optically enriched forms,respectively. In this way, interesting chiralbifunctional building blocks, some of them bearing newly createdstereogenic quaternary centers,have been efficiently synthesized.
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