A Theoretical Study on the Alkylation of the Ambident Enolate from a Methyl Glycinate Schiff Base

作者：Nahm Keepyung^*; Lee Seungmin

来源：BULLETIN OF THE KOREAN CHEMICAL SOCIETY, 2012, 33(8): 2711-2718.

DOI：10.5012/bkcs.2012.33.8.2711

• Ambident enolate
• Enolate alkylation
• Density functional theory (DFT)

The alkylation of the ambident enolates of a methyl glycinate Schiff base with ethyl chloride was studied at B3LYP and MP2 levels with 6-31+G* basis set. The free (E)-enolates and (Z)-enolate are similar in energy and geometry. The transition states for the alkylation of the free (E)/(Z)-enolate with ethyl chloride have similar energy barriers of similar to 13 kcal/mol. However, with a lithium ion, the (E)-enolate behaves as an ambident enolate and makes a cyclic lithium-complex in bidentate pattern which is more stable by 11-23 kcal/mol than the (Z)-enolate-lithium complexes. And the TS for the alkylation of (E)-enolate-lithium complex coordinated with one methyl ether is lower in energy than those from (Z)-enolate-lithium complexes by 4.3-7.3 kcal/mol. Further solvation model (SCRF-CPCM) and reaction coordinate (IRC) were studied. This theoretical study suggests that the alkylation of ambident enolates proceeds with stable cyclic bidentate complexes in the presence of metal ion and solvent.

• 出版日期2012-8-20