Alkyl Radical Generation in Water under Ambient Conditions-A New Look at the Guareschi Reaction of 1897

摘要

In a series of papers initially published between 1897 and 1901, I. Guareschi (Turin) and his colleagues reported the synthesis of 4,4'-dialkyl-3,5-dicyanoglutarimides by the condensation of ketones other than acetone with ethyl cyano-acetate in ethanolic ammonia. The reaction has frequently been used subsequently as a route to functional quaternary centers, and because glutarimides have shown potential as drugs. In Guareschi's work, these otherwise unremarkable compounds demonstrated a remarkable property. The imide la, on neutralization with alkaline ammonia or Mg(OH)2, gave pyridone 2 with evolution of ethane [Eq. (1)]. Likewise, hydrocarbons RH (R = Et, Pr, nBu, n-C6H13, Me2C=CH-CH2CH2, n-C9H19) were formed starting with glutarimides derived from ketones RCOMe. This aspect of Guareschi's work appears to have been at best neglected, at worst forgotten.