Metal-Metal Exchange of α-Metallo Ketones. Novel Formation of α-Acyl Anion and α-Keto Carbonium Ion Equivalents from (Aryl)phenacyl TlIII, PbIV, and HgII Systems

Article abstract of DOI:10.1021/jo00240a016

The novel class of α-metallo ketones RCOCH2Tl^IIItolyl(OCOCF3) where R = phenyl, substituted phenyl, thienyl, pyridinyl, and tert-butyl have been synthesized and characterized by 1H NMR and 13C NMR.These compounds serve as anion equivalents in the TiCl4-mediated aldol condensation.Metal-metal exchange with iodosylbenzene or lead tetraacetate leads to α-nucleophilic substitution derived from the formal α-keto carbonium ion equivalent.The corresponding p-CH3OC6H4COCH2Pb^IVC6H4OCH3-p-(OCOCH3)2 and (p-CH3OC6H4COCH2)2Hg^II analogues were synthesized and shown to likewise behave as either enolate anion or α-keto carbonium ion equivalents upon metal-metal exchange with Ti^IV, Pb^IV, or I^III.The importance of this work is that the range of reactivity of α-metallo ketones may be selectively adjusted by metal-metal or metal-metalloid exchange.