Reaction of a-keto imines with the in situ generated acetylcobalt tetracarbonyl occurs only at the carbon-nitrogen double bonrtove B-keto amides. An unexpected by-product was formed in several instances. The acylation of dienes, trienes*, and fulvenes3 by the in situ generated acetylcobalt -tetracarbonyl is a useful synthetic transformation. In addition, the use of allenes as substrates results in hydroxyacylation4. These reactions are all regiospecific. Although simple olefins do not react with CH3COCo(C0)4, it seemed conceivable that the organometallic compound would add to the carbon-nitrogen double bond of an imine since there is polar character in such a bond. Chosen as the substrates for this investigation were cc-keto imines, easily prepared in high yields by reaction of a-diketones with an appropriate amine5. The use of these carbon-nitrogen double bond systems as reactants would also provide information on the selectivity of the process. Triethylborohydrides are useful reagents in organometallic synthesis, one example being the formation of metal carbonyl anions from neutral precursors 637 . Gladysz has noted that, in addition to the organometallic anions, produced" in these reactions6. "only the volatile by-products H2 and (C2H5)3B are We used this method [Na(C,H,),BH,Co,(CO),] to form COAX, and subsequently CH3COCo(C0)4 [by adding methyl iodide under a CO atmosphere]. Treatment of the in situ generated CH3COCo(C0)4 with 1,R=4-CH3C6H4 or 4-CH30C6H4, at --60ยฐC in tetrahydrofuran (THF), afforded the 8-keto amides 2 in 74-88% yield, 3 being obtained as low yield by-products (Table 1). We were surprised to observe the formation of the ethyl amide 4 (R=Ph) in 32% yield when 1, R=Ph, was used as the reactant [g, R=Ph, was obtained in 40% yield]. The yield of 4, R=Ph, increased to 40% when the reaction was repeated in the absence of methyl iodide. Furthermore, 4, R=p-CH30C6H4, was isolated in ZO-25% yield when 1, R=p-CH30C6H4, was treated (CO atm.) with the solution obtained from Na(C2H5)3BH and Kh co2(co)8 Na(C2H5)3BH THF> Co(CO)y !!$ CH3COCo(C0)4 PhCC=NR @), PhCOCHN 0R + PhCOCHNHR + PhCOCHN /R ' 'COCH I \ Ph 3 ;h Ph COC2H5 (2) (3) (4)