Building an extended inverse crown motif via alkali-metal-mediated alpha-magnesiation of furan

The utility of inverse crown chemistry is extended to aromatic heterocycles, as furan is deprotonated selectively at the a-position by the mixed-metal alkyl-amido base [(TMEDA)Na-.(Bu-n)(TMP)Mg(TMP)] to generate a transient intermediate which undergoes disproportionation to the disodium dimagnesium hexafuryl tri(thf) complex [{{(thf)(3)Na-.(2)}{(TMEDA)Mg-.(2)}(2-C4H3O)(6)}(infinity)], a new type of inverse crown structure with triply-stabilized (through Mg-C sigma, Na-O sigma and (NaC)-C-...-C pi interactions) furyl 'guest' anions, and the tris(amide) [(TMEDA)(x)(NaMg)-Na-.(TMP)(3)]