ALKYLIRON AND ALKYLCOBALT REAGENTS .9. RE ARRANGEMENT OF ALIPHATIC TERMINAL EPOXIDES TO METHYL KETONES BY IRON ALKYL REAGENTS INSTEAD OF CO2(CO)8 OR NOBLE-METAL CATALYSTS

The highly selective rearrangement of aliphatic terminal epoxides to m ethyl ketones, hitherto possible only with Co2(CO)8 or noble metal cat alysts, occurs smoothly with Me4-FeLi2, Me3FeLi, or the catalytic syst ems [RLi + 2.5 mol% FeCl3] (R = Me, Bu). This was demonstrated by the rearrangement of 1-decene oxide (1) to 2-decanone (2) (yield 80-81%; T able 1) and 6-bromo-1-hexene oxide (5) to 6-bromo-2-hexanone (6) (yiel d 78%, Me4FeLi2 applied only). The competition reaction of Me4FeLi2 wi th 1 and 2-octanone (8) (mole ratio 0.5:1:1) led to 87% 2-methyl-2-oct anol (9) and not to the rearrangement 1 --> 2. This indicates that Me4 FeLi2 -in contrast to the opposite behavior of organo cuprates -reacts faster with ketones than with the aliphatic terminal epoxides. By tre atment of 1 with methyl derivatives of Mn(II), Co(II), and Ni(II) or w ith Bu4FeLi2 (Table 2) other products (3, 4) besides 2 were formed. Th e rearrangement of 1 with Me4FeLi2 is assumed to start with an oxidati ve addition and yields 2 as its Li or Fe enolate (trapped with acetanh ydride to give 64% of 20) after reductive elimination of CH4. The cata lytic rearrangement of 1 with [MeLi + 0.25 mol% FeCI3] very probably o ccurs in an analogous manner with an super-ate complex Me4FeLi2(MeLi)n as the active species and the Li enolate of 2 as end product (Scheme 4). The aromatic terminal epoxides styrene oxide and alpha-methylstyre ne oxide give various products in the reaction with Me4FeLi2 or Me3FeL i, including the deoxygenation products styrene and alpha-methyl-styre ne. These products are exclusively formed on treatment of the epoxides with Me4MnLi2. (Prepared, hitherto in the literature not described co mpounds: 7 and 10-15.)