Donor–acceptor-stabilised germanium analogues of acid chloride ester and acyl pyrrole compounds: synthesis and reactivity

摘要

Germaacid chloride, germaester, and N-germaacyl pyrrole compounds were not known previously. Therefore, donor–acceptor-stabilised germaacid chloride (i-Bu)2ATIGe(O)(Cl) → B(C6F5)3 (>1), germaester (i-Bu)2ATIGe(O)(OSiPh3) → B(C6F5)3 (>2), and N-germaacyl pyrrole (i-Bu)2ATIGe(O)(NC4H4) → B(C6F5)3 (>3) compounds, with Cl–GeO, Ph3SiO–GeO, and C₄H₄N–GeO moieties, respectively, are reported here. Germaacid chloride >1 reacts with PhCCLi, KOt-Bu, and RLi (R = Ph, Me) to afford donor–acceptor-stabilised germaynone (i-Bu)₂ATIGe(O)(CCPh) → B(C₆F₅)₃ (>4), germaester (i-Bu)₂ATIGe(O)(Ot-Bu) → B(C₆F₅)₃ (>5), and germanone (i-Bu)₂ATIGe(O)(R) → B(C₆F₅)₃ (R = Ph >6, Me >7) compounds, respectively. Interconversion between a germaester and a germaacid chloride is achieved; reaction of germaesters >2 and >5 with TMSCl gave germaacid chloride >1, and >1 reacted with Ph₃SiOLi and KOt-Bu to produce germaesters >2 and >5. Reaction of N-germaacyl pyrrole >3 with thiophenol produced a donor–acceptor-stabilised germaacyl thioester (i-Bu)₂ATIGe(O)(SPh) → B(C₆F₅)₃ (>10). Furthermore, the attempted syntheses of germaamides and germacarboxylic acids are also discussed.