Metal catalysed reactions of β,β′-tricarbonyl derivatives with isocyanates

The reactions of β,β′-tricarbonyl derivatives with isocyanates are catalysed by 2 mol % transition metal acetylacetonates (e.g., [Co(acac)2] and [Zn(acac)2]) at room temperature. 3-Oxo-1,5-pentanedioic acid dimethylester (1) reacts with RNCO (R=Et, CH2CHdouble bond; length as m-dashCH2, CH2Ph, Ph, 4-Cl–Ph) to give 1:1 adducts involving the formation of a new C–C bond between the intercarbonylic methylene and the isocyanato group. Under similar conditions 2,4,6-heptanetrione (2) reacts with the same isocyanates to afford pyridinone and pyranone derivatives resulting from the cyclisation of unstable 1:1 and 1:2 adducts.