Regioselective 1,4- and 1,6-Conjugate Additions of Grignard Reagent-Derived Organozinc(II)ates to Polyconjugated Esters
作者:Manabu Hatano、Mai Mizuno、Kazuaki Ishihara
DOI:10.1021/acs.orglett.6b01774
日期:2016.9.16
Regioselective synthetic methods were developed for 1,4- and 1,6-conjugateadditions of Grignard reagent-derived organozinc(II)ates to malonate-derived polyconjugated esters. By taking advantage of the tight ion-pair control of organozinc(II)ates, it was possible to switch between 1,4- and 1,6-conjugateadditions by introducing a terminal ethoxy moiety in the conjugation.
Bondlengths are widely utilised as observable structure parameters to estimate the contributions of particular resonance structures. Herein, it is demonstrated that outstandingly strong electron-withdrawing groups can reverse the textbook bond-length alternation order in polyene systems. This is a pronounced aberration from the molecular structure predicted by the neutral Lewis resonance form.