ABSTRACT
The application to organic synthesis of complexes formed by transition- metal ions and organic ligands is a rapidly expanding field. However, there are, as yet, relatively few reactions that can be applied to a wide range of compounds. Reaction of the amine with cyclopentadienyltitanium trichloride, and loss of two moles of hydrogen chloride, gives the metal imido complex, which undergoes addition with the alkyne. Alkene metathesis, by intramolecular addition of the metal carbene to the alkene and fragmentation of the bicyclo metallocyclobutane, gives the dihydrofuran and tungsten carbine. The chemistry of organometallic transition-metal compounds is marked by the tendency of the metal to achieve an electronic configuration corresponding to that of the next noble gas. The process is superior to the Wittig reaction in two circumstances: first, if an asymmetric carbon atom with an enolizable proton is adjacent to the carbonyl group, it retains its stereochemical integrity; second, highly hindered carbonyl compounds react more efficiently.
