Most commonly, E is an oxygen atom, so that the reaction results in terminal alkenes from aldehydes and ketones, or more rarely, enol ethers from esters or enamines from amides.
Photolysis of a solution of diazomethane in n-pentane gives a mixture of hexanes and higher homologues.
[9] An enolate is generated by deprotonation of the α-C–H bond using a hindered lithium amide (LiNR2) base (e.g., LDA, LHMDS).
Subsequently, the enolate is reacted with Eschenmoser's salt ([Me2N=CH2]+I–) to give a β-dimethylamino carbonyl compound (Mannich base).
The Mannich base is then subjected to methylation or N-oxidation to give a trimethylammonium salt or amine N-oxide, which is then subjected to Hofmann elimination or Cope elimination, respectively to give the α-methylene carbonyl compound.