Synthesis of 2-ferrapyridine complexes and their use as precursors for substituted pyridinones and pyrroles
- Pennsylvania State Univ., University Park, PA (United States); and others
The 2-ferra-3-azetine complexes Fe{sub 2}({mu}-CHCH{double_bond}NR)(CO){sub 6}, which form from the reaction of Fe{sub 2}({mu}-CH{sub 2})(CO){sub 8} with phosphinimines, have been found to react photochemically with a variety of alkynes (R{sup 1}C{triple_bond}CR{sup 2}) by inserting the alkyne into the four-membered metallacycle to give the 2-ferrapyridine complexes Fe{sub 2}({mu}-C(R{sup 1})C(R{sup 2})CHCH{double_bond}NR)(CO){sub 6}. Two of the 2-ferrapyridine complexes have been crystallographically characterized and shown to consist of six-membered metallacycles having adjacent iron and nitrogen atoms with this metallacycle {pi}-coordinated to the second iron atom by three carbon atoms and an Fe-Fe bond. Terminal alkynes (R{sup 1} = Me, Ph, Bu{sup t}, SiMe{sub 3}) undergo the insertion regioselectively to give only the 2-ferrapyridine isomer with the substituted carbon adjacent to the iron atom. Unsymmetrical internal alkynes insert to give generally a mixture of isomers which is influenced by the steric and electronic nature of the alkyne substituents. The 2-ferrapyridine complex Fe{sub 2}({mu}-C(Ph)CHCHCH{double_bond}NBu{sup t})(CO){sub 6} was shown to undergo a ring contraction when heated at 160 {degrees}C under CO (500 psi) to five the new 2-ferra-3-azetine complex Fe{sub 2}({mu}-C[CH{double_bond}C(Ph)(H)]CH{double_bond}NR)(CO){sub 6}, which has also been crystallographically characterized and has a vinyl substituent attached to the 3-carbon of the 2-ferra-3-azetine ring. When heated, the 2-ferrapyridine complexes released 2-pyridinones and pyrroles with the ratio of these products dependent upon the ring substituents and the conditions employed. 21 refs., 3 figs., 9 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 555009
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 2 Vol. 11; ISSN 0276-7333; ISSN ORGND7
- Country of Publication:
- United States
- Language:
- English
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