Functionally substituted vinyl carbanions, 44. Synthesis of odd-numbered 13-crown-4 derivatives possessing a functional group and their application in C-lithiation of acrylates

The synthesis of symmetrically hydroxy‐substituted 13‐crown‐ 4 derivatives 2 and 3 is reported. To this end, diol 7 is first deprotonated with potassium tert‐butoxide and then treated with ditosylate 6 in the presence of lithium perchlorate as a template. Base‐catalyzed addition of 2 and 3 to methyl propiolate affords β‐alkoxy‐substituted acrylates 1a and 1b, respectively. Treatment of 1a with LDA in THF generates the β‐C‐lithiated species 1a‐A as indicated by quenching with CH3OD and reaction with propanal; thus, β‐deutero derivative 1a‐(β‐D) and tetronate 4a, respectively, are obtained. Competition experiments between 1a and methyl β‐methoxyacrylate (1c) with LDA in THF exhibit for 1a a higher thermodynamic but practically the same kinetic acidity.