Reaction of tetracarbonylferrate with activated vinyl halides to give (1–3-η-acryloyl)tricarbonylferrates and alkenyltetracarbonylferrates

Abstract

Disodium tetracarbonylferrate reacts with activated vinyl halides in tetrahydrofuran under ambient conditions to give products which depend on the starting halide. The reactions of dimethyl 2-chloroethylene-1, 1-dicarboxylate, methyl Z-3-chlorocrotonate, E-2-chlorovinyl t-butyl ketone, and E-2-chlorovinyl phenyl ketone give the corresponding 1–3-η-acryloyltricarbonylferrates and have been isolated as bis(triphenylphosphine)iminium salts (4b)–(4e) in yields of 20–60%. Methyl E-3-bromo-2-methylacrylate, 1-chloro-2,2-dicyanoethylene, and E-β-bromostyrene give the corresponding alkenyltetracarbonylferrates (5f)–(5h), E-3-bromoacrylate a ca. 1 : 1 mixture of 1–3-η-acryloyl-(4i) and alkenyl-ferrates (5i), and methyl E-3-chlorocrotonate an unusual 1–3-η-acryloyl complex (4j) derived by a 1,3-hydrogen shift. Protonation of (4) and (5) results in tetracarbonyl(η-olefin)iron complexes. The geometry of the starting vinyl compounds is fully retained in the products. Methylation of (4b) with SFO₂(OMe) gives {1–3-η-[2,2-bis(methoxycarbonyl)vinyl]methoxycarbene}tricarbonyliron (9).