Reissert-like Alkenylation of Azaaromatic Compounds with Alkenylzirconocene Chloride Complexes

Reissert‐Type Acylation with Acylzirconocene Chloride Complexes

“…Since α‐ketols 12 were obtained in 4–9 % yields in the Reissert‐type acylation of quinolines by Cu I /CH 2 Cl 2 catalytic systems, the acyl Cu species might be involved in these preferred 1,4‐addition reactions. Such a preferential formation of 1,4 adducts has been reported in Reissert‐type transformations of quinolines and pyridines by using organocopper compounds8a–8c or organometallic compounds with Cu I additives 5e,6d,8d,8e. Although details about the solvent effect22 and the role of the cationic Rh I catalyst23 for the regioselectivity remain uncertain at present, the cationic Rh I catalyst might take part in promoting the generation of N ‐acylquinolinium intermediates 13 24…”

“…Based on our previous studies of the Reissert‐type alkenylation reaction,5d,5e our preliminary examinations focused on the reaction of isoquinoline ( 2a ) with acylzirconocene chloride 1 (2 equiv.) in the presence of ClCO 2 Et (1.2 equiv.)…”

“…These procedures, however, could not be applied to azaaromatic compounds. Our recent extensions to the reaction of azaaromatics with alkenylzirconocene chlorides (Cp = cyclopentadienyl) brought about Reissert‐type alkenylation of azaaromatics activated by chloroformates (Scheme b) 5d,5e. Thus, we expected that the nucleophilic acylation of azaaromatics with acylzirconocene chlorides would be achieved by Reissert‐type transformations using chloroformates.…”