Addition of alkynes to (vinylketene)tricarbonyliron(0) complexes

Abstract

Alkynes add to (vinylketene)tricarbonyliron(O) complexes to generate stable adducts; addition of unsymmetrical alkynes is highly regioselective and the regiochemistries of the adducts produced in these reactions were determined by X-ray crystal structure analyses of the major isomer derived from but-3-yn-2-one and (3-tert-butyl-5-phenyl-I -0xapenta-I ,2,4-triene)tricarbonyIiron(O), and of the structurally modified product derived from diethylpropynylamine and (3-isopropyl-5-phenyl-I -0xapenta-I ,2-4-triene)tricarbonyIiron(O).

Tetraaminocyclopentadienone Iron Complexes as Hydrogenation Catalysts

“…The quaternary carbon atoms of the metallacycle give rise to signals at 220.6 (C1/C6), 172.2 (C3/C4), and 68.4 ppm (C2/C5), respectively, which is in good agreement with the values found for the ferracyclobutenones 2 and other η 2 -vinyl complexes . It should be noted, however, that iron complexes with a η 2 -vinyl/1-metallacyclopropene motif are exceedingly rare, and we are only aware of one structurally characterized mononuclear η 2 -vinyl−η 3 -allyl complex . In addition, a few dinuclear complexes were obtained from the reactions of Fe 2 (CO) 9 with diethylaminoalkynes, which contain bridging Et 2 NCCR units with similar iron-aminocarbene subunits. − To the best of our knowledge, a related bis­(η 2 -vinyl) complex is unknown to date.…”

“…105 It should be noted, however, that iron complexes with a η 2 -vinyl/1metallacyclopropene motif are exceedingly rare, and we are only aware of one structurally characterized mononuclear η 2vinyl−η 3 -allyl complex. 106 In addition, a few dinuclear complexes were obtained from the reactions of Fe 2 (CO) 9 with diethylaminoalkynes, which contain bridging Et 2 NCCR units with similar iron-aminocarbene subunits. 107−110 To the best of our knowledge, a related bis(η 2 -vinyl) complex is unknown to date.…”

Pyrrole Formation via Reactivity of η4-(Vinylketenimine)iron Complexes with Electron-Deficient Alkynes

“…Additionally, the iron complexes of vinylketenes exhibit noteworthy synthetic transformations. , For example, electron-deficient alkynes add to the vinylketene complexes via insertion to yield stable 1:1 adducts (eq ). However, the particulars of the reactivity of η 4 -(vinylketenimine)­iron complexes, , which are easily prepared from the corresponding (vinylketene)iron complexes, are largely unknown. On the basis of η 4 -(vinylketene)iron complexes reactivity (eq ), we envisaged that (vinylketenimine)iron complexes could be converted into η 3 -allyl iron complexes through alkyne insertion.…”