Ferrocene Compounds. XXVI. C- and O-Ferrocenylalkylation of Methyl Salicylate

Reaction of equimolar amounts of methyl salicylate, sodium and N,N,N-trimethylferrocylammonium iodide (1a) in ethanol gave 55% of ethyl 1-ferrocenylethyl ether (4). By refluxing a solution of 9 mmol sodium and 3 mmol of FcCHRNMe3I (1a, R = H; 1b, R = Me; 1c, R = Ph) in a large excess of methyl salicylate for 2-3 hours, the corresponding methyl 5-ferrocylsalicylates (5) (10-23%) and methyl-3-ferrocylsalicylates (6) (12-20%) were obtained. During conversion of salt 1b, besides of 5b and 6b, 20% of vinylferrocene (7) and 6% of 1-ferrocenylethyl methyl ether (8) were isolated. Under the same conditions as in conversions 1 → 5, 6 2-ferrocenylethyl acetate (11) and methyl salicylate failed to react, and 2-ferrocenylethyl bromide (12) was transformed to 12% of methyl o-(2-ferrocenylethoxy)benzoate (13) and 25% of methyl 5-(2-ferroceny-lethyl)salicylate (14), as well as 10% of vinylferrocene (7). The mechanisms of reactions 1 → 5, 6 and 12 → 13, 14 are discussed, suggesting a stabilization effect by ferrocene nucleus in the intermediate α- and β-ferrocenyl carbocations