Description:
<jats:p><jats:bold>Chain Expansion of Functionalized Alkanones by Rearrangement Reactions</jats:bold></jats:p><jats:p>In analogy to the transamidation reactions which were published earlier a method is described to prolong aliphatic C‐chains by two or four C‐atoms. 1,3‐Diketones or 2‐nitro alkanones which are monosubstituted at C(2) are condensed with <jats:italic>e.g.</jats:italic> methyl vinyl ketone. The reaction product is transformed to its chain‐prolonged isomer in the presence of strong base <jats:italic>via</jats:italic> a 4‐ or 6‐membered intermediate. The most effective reagent for the <jats:italic>Michael</jats:italic> reaction is methyl 3‐oxo‐4‐pentenoate (<jats:bold>20</jats:bold>). In this case it was possible to convert 3‐nitro‐2‐butanone (<jats:bold>21</jats:bold>) to methyl 2‐acetyl‐6‐nitro‐3‐oxoheptanoate (<jats:bold>26</jats:bold>) in 82% yield.</jats:p>