Iron Aminocarbene Complexes Containing a Double CC Bond in the N-Substituent:  Preparation and Reactivity

Abstract

Reaction of N,N-diallylbenzamide with Na2Fe(CO)4 and Me3SiCl afforded chelated cis-tricarbonyl[(η2-N-allyl-N-allylamino)(phenyl)carbene]iron(0) directly. The same reaction of N-(3-buten-1-yl)-N-methylbenzamide proceeded with migration of the double bond to the allylic position, giving a mixture of chelated cis-tricarbonyl[(η2-N-(2-butenyl)-N-methylamino)(phenyl)carbene]iron(0) and nonchelated tetracarbonyl[(N-(2-butenyl)-N-methylamino)(phenyl)carbene]iron(0). N-(3-Buten-2,2-dimethyl-1-yl)-N-methylbenzamide, in which migration of double bond is not possible, gave a mixture of E and Z isomers of nonchelated tetracarbonyl[(N-(2,2-dimethyl-3-butenyl)-N-methylamino)(phenyl)carbene]iron(0). Thermolysis of the latter furnished 1-methyl-3,3-dimethyl-6-phenyl-1,2,3,4-tetrahydropyridine as the only product.

Syntheses, structures and electrochemistry of some 1-(η2-allylamino)-1-ferrocenylcarbene complexes of chromium(0), molybdenum(0) and tungsten(0)

“…Stable metallacyclic (g 2 -alkene)carbene complexes of group VI transition metals [2][3][4][5][6] are ideal model systems for studying the elementary steps in olefin cyclopropanation [7][8][9][10] and metathesis [11][12][13][14]. This has been done at length by varying the central metal, the ancillary ligands and the alkene residues, as well as the spatial orientation of the g 2 -bonded ligands by adjusting the tether length.…”

Introduction of a phosphorus ylide moiety into [η2-(ω-hydroxy)alkenyl]chromium(0) carbene complexes with Ph3PCCO and consecutive Wittig alkenations with 2-alkynals. Part 12: the chemistry of metallacyclic alkenylcarbene complexes

“…Synthesis of chelated (g 2 -alkadienynyl)carbene complexes (OC) 4 Cr@C[(4,5-g 2 )NMeCH 2 CH@CHCH 2 O 2 -C-CH@CH-CBC-R 2 ]R 1 (4)(5)(6) Ylide-terminated complexes 3 undergo clean Wittig alkenation reactions with aldehydes under surprisingly mild conditions (4-10 h, r.t.). Sterical shielding of the ylide portion by the alkene-carbene complex core is obviously neglectable.…”

“…Table 1 13 C NMR data a;b;c of the complexes 3a/3a 0 and 3b/3b 0 systems for domino alkene-alkyne-carbene processes we reacted exemplary 2-alkynals, R 2 -CBC-CHO with 3 to give the expected product complexes (OC) 4 Cr@C[(4,5-g 2 )NMeCH 2 CH@CHCH 2 O 2 C-CH@CH-CBC-R 2 ]R 1 (4)(5)(6) as orangebrown, moderately air-stable powders in good yields (Scheme 2). These can be purified and separated from triphenylphosphane oxide, Ph 3 PO, by filtration and consecutive flash chromatography (silica gel; diethyl ether).…”

“…Stable metallacyclic carbene-(g 2 -alkene) complexes of group VI transition metals [2][3][4][5][6] are ideal model systems for studying the sterical and electronical requirements and limitations of the elementary steps in olefin cyclopropanation [7][8][9][10] and metathesis [11][12][13][14] processes. They can in principle be fine-tuned by the choice of the central metal and of the ancillary ligands, and by adjusting the spatial orientation of the g 2 -bonded ligands via the length of the tether between them.…”

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

“…Addition of η 4 -(vinylketenimine)iron complex to ethyl propiolate resulted in formation of an enolate intermediate I , stimulated by the nucleophilic nitrogen atom of the ketenimine . Subsequent intramolecular addition of enolate to the keteniminium moiety occurred at C-2 8 to yield a η 3 -vinylcarbene intermediate II . ,, Complex II then underwent a dominant 1,2-styryl group migration, , which suppressed the 1,2-migration of the alkyl group (R 2 ) probably due to the coordination of a styryl double bond to iron.…”