Use of the Nonionic Superbase P(MeNCH 2 CH 2 ) 3 N in the Selective Monoalkylation of Active-Methylene Compounds

  • 10.1021/jo972350i
  • The Journal of Organic Chemistry
  • p 3677-3679, Volume 63, Issue 11,
  • journal-article
The symmetric active-methylene compounds CH 2 (CO 2 Et) 2 and CH 2 [C(O)Me] 2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic superbase P(MeNCH 2 CH 2 ) 3 N in 85−98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO 2 CCH 2 C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59−88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH 2 CH 2 ) 3 N + counterion in a tight ion pair.


Not reproducible. Experimental produced mixture

This paper by Verkade and co-workers describes a superbase P(MeNCH2CH2)3N mediated selective monoalkylation of active-methylene compounds. Although malonate alkylation has been known for many years, it is very difficult to obtain really good yields for mono-alkylation of...