ALKYLIRON AND ALKYLCOBALT REAGENTS .8. ALKYL-IRON(II) COMPOUNDS AS REAGENTS AND CATALYSTS FOR THE TRANSFORMATION OF ACYL CHLORIDES INTO KETONES

Me2Fe, Bu2Fe, Me3FeLi, or Bu3FeLi - prepared in situ by reduction of F eCl3 to FeCl2 and subsequent alkylation with MeLi, MeMgBr, BuLi, or Bu MgBr - are useful reagents for the conversion of acyl chlorides into k etones. The system (RMgX + catalytic amount of FeCl3) react like the a lkyl Fell reagents with acyl chlorides to give ketones even at -65-deg rees-C. Competition experiments with benzoyl chloride/2-methoxybenzoyl chloride show that the selectivity increases (competition constants K (k) = 9.9,10.7,10.9,15.0, ca. 110) in the sequence MeFeCl, Me2Fe, Me3F e(MgBr), Me4Fe(MgBr)2, and catalytic system [MeMgBr + 2.5 mol % FeCl3] (= 2, 3, 4, 5, and 40 MeMgBr per 1 FeCl3, respectively). A new hypoth esis on the nature of the active catalyst is discussed.