Intermolecular Hydroamination of Methylenecyclopropane Catalyzed by Group IV Metal Complexes

Abstract

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Selectivity in Metal‐Catalyzed CarbonCarbon Bond Cleavage of Alkylidenecyclopropanes

“…[36,37] This observed selectivity is opposite to all the ones discussed previously (and is identical to ring-opening reaction of radical species) [38] and could be understood on the basis of a weak coordination of the metal by the adjacent p-electrons of the arene ring. Such interactions would favor a synorientation of M-C and C2/C3 bonds, which would lead to preferential C2/C3 cleavage.…”

“…[31] Recent studies on the ring-opening of monoactivated MCPs led to efficient preparations of various heterocyclic structures, but as the selectivity of the ring-opening is either dictated by the presence of the activating group (Michaeltype addition), [34] or by the ring-opening of bicyclic carbocation intermediates, [35] it will not be treated in details here. Finally, organolanthanide- [36] as well as titanium-mediated [37] intermolecular hydroamination reactions of MCPs represent an important class of transformation. When unsymmetrical phenylmethylenecyclopropane is treated with various amines in the presence of organolanthanide complexes…”

“…, [37] the 1,2-addition 57 is initially observed (no traces of 2,1-addition adducts 58 was detected) ensuing b-alkyl eliminative cyclopropane ringopening of the Ln-alkyl cyclopropane species 57 to afford mainly the linear imine products after protonolysis and tautomerization (Scheme 23). [36,37] This observed selectivity is opposite to all the ones discussed previously (and is identical to ring-opening reaction of radical species) [38] and could be understood on the basis of a weak coordination of the metal by the adjacent p-electrons of the arene ring.…”

Aminopyridine stabilized group-IV metal complexes and their applications

“…Some other researchers such as Markku, Smithies', Wheatley's and Sakai group have also synthesized the titanium complexes [42,46]. The main focus for the synthesis of titanium complexes was their coordination/organometallic chemistry as well as application in olefin polymerization and hydroamination catalysis [45]. Mostly, the titanium precursor TiCl 4 and lithium/sodium/potassium salts of the respective ligands have been employed and the mono/bis/tris/tetrakis-Ap-titanium complexes (depending upon the stoichiometric ratio of ligand and metal salt) have been synthesized, but mono/ bis complexes contain two cis chlorides and, hence, are more interesting for catalytic applications [42].…”

“…13) and shorter amido-N-Hf bond than the pyridine-N-Hf bond indicating the location of negative charge on amido nitrogen atom [34]. Zr-complexes (33)(34)(35)(36)(37)(38) and Hf-complexes (43)(44)(45)(46)(47)(48) showed moderate activities for ethylene polymerization which has been presumed due to poor stability in the presence of aluminum alkyls [26,30,34]. Kempe et al hypothesized that diamine (containing an amine function at two and six position of pyridine ring)-functionalized ligands (electron rich-ligands) could enhance the stability of complex, and, hence, synthesized Hf-complexes containing electron-rich ligands through toluene elimination route [34].…”