The First Benzo[1,2:4,5]dicyclobutenones and Their Tricarbonylchromium Complexes

2011 ◽  
pp. n/a-n/a ◽  
Author(s):  
Ismail Abdelshafy Abdelhamid ◽  
Osama Mahmoud Ali Habib ◽  
Holger Butenschön
Keyword(s):  
Tricarbonylchromium Complexes

6π-Tricarbonyl-Komplexe von Pyridin-Derivaten, Synthesen und Reaktionen / 6π-Tricarbonyl-Chromium Complexes of Pyridine Derivatives, Syntheses and Reactions

1984 ◽  
Vol 39 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Karl Dimroth ◽  
Rüdiger Thamm ◽  
Hans Kaletsch
Keyword(s):  
Hydrogen Atom ◽  
Phosphorus Atom ◽  
Nmr Spectra ◽  
Pyridine Derivatives ◽  
Chromium Complexes ◽  
X Ray ◽  
Chromium Hexacarbonyl ◽  
Allyl Rearrangement ◽  
Tricarbonylchromium Complexes ◽  
C Nmr

New 6π-tricarbonylchromiumpyrnftne complexes 5c and 5d could be synthesized from 2,6-di-rbutyl- and 2,4,6-tri-f-butylpyridines (3c and 3d) with chromium hexacarbonyl. They are characterized by their 1H and 13C NMR Spectra and their CO-frequencies which are rather similar to those of 6π-tricarbonylchromium-2,4 ,6-triphenyl [1] or 2,4,6-trw-butyl- [2] λ3-phosphorins. When 5d is reacted with lithiumphenyl, the phenyl residue adds to C-4, giving probably compound 7, which by methanolysis and allyl rearrangement of the hydrogen atom from position 4 to position 2 affords tricarbonylchromium-2,6-di-f-butyl-4-phenyl-1,2-dihydropyridine (8) in 56% yield. The 6π-tricarbonylchromium complexes of 2,4,6-triphenyl- or 2,4,6-tn-t-butyl-λ3-phosphorins react with lithiumorganic compounds by addition only to the phosphorus atom whose reaction with methyliodide lead to tricarbonylchromium-λ5-phosphorin-ylid complexes [2], 5 d is a well crystallized compound, the X-ray analysis of the first 6π-tricarbonylchromium pyridine derivate could be performed [3] and compared with the results of the X-ray analysis of 6π-tricarbonylchromiumx 2,4,6-triphenyl-λ3-phosphorin [4]

Reactivity of (η6-Arene)tricarbonylchromium Complexes toward Additions of Anions, Cations, and Radicals

2001 ◽  
Vol 123 (21) ◽  
pp. 4904-4918 ◽  
Author(s):  
Craig A. Merlic ◽  
Michael M. Miller ◽  
Bruce N. Hietbrink ◽  
K. N. Houk
Keyword(s):  
Tricarbonylchromium Complexes

Chiral Auxiliary-Directed Asymmetric Ortho-Lithiation of (Arene)tricarbonylchromium Complexes

1997 ◽  
Vol 62 (23) ◽  
pp. 8264-8267 ◽  
Author(s):  
Jin Wook Han ◽  
Seung Uk Son ◽  
Young Keun Chung
Keyword(s):  
Chiral Auxiliary ◽  
Tricarbonylchromium Complexes

Arene chromium complexes with functionalized anellated rings. Selective formation of highly substituted polycycles

2002 ◽  
Vol 74 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Holger Butenschön
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Ring Expansion ◽  
Chromium Complexes ◽  
Ketone Group ◽  
Aldol Additions ◽  
Cope Rearrangements ◽  
Hydrolysis Of ◽  
Selective Formation ◽  
Tricarbonylchromium Complexes

Tricarbonylchromium complexes of benzocyclobutenone, benzocyclobutenedione, and 1,3-indandione are readily prepared by hydrolysis of the complexes of the corresponding acetals. Reduction of the benzocyclobutenone complex gives rise to an oxy-anion-driven ring opening to the corresponding ortho-quinodimethane intermediate, which can be trapped with dienophiles. Addition of 1-ethoxy-1-lithioethene allows a stereoselective ring expansion followed by an anionic ketol rearrangement with complete diastereoselectivity. Addition of 1-lithio-1-methoxyallene gives rise to a rare anionic 1-vinylcyclobutenol-cyclohexadienol rearrangement. Diaddition of alkenylmetal reagents at both keto groups in benzoyclobutenedione complexes causes dianionic oxy-Cope rearrangements to occur at ­78 °C, which are followed by diastereoselective intramolecular aldol additions. In some cases, a completely regioselective mono hydrolysis of di(enolates) was observed. Dianionic oxy-Cope rearrangements can also be realized with unstrained benzil derivatives giving 1,6-hexanediones and the corresponding aldol adducts. The 1,2,3-indantrione complex is obtained by oxidation of the 1,3-indandione complex with dimethyldioxirane in good yield and reacts with its central ketone group in hetero Diels­Alder cycloadditions.

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