Tricarbonyl 1,3,5-cycloheptatriene

Later on, it was demonstrated that these heterocycles can undergo Diels-Alder reactions in the presence of an electrophile (Ss or Mel) and dienophiles <2002T1573, 2003HAC560>. These phosphoms-containing heterocycles were found to produce, upon reaction with tricarbonyl(cycloheptatriene)molybdenum(0) or tricarbonyl(mesitylene) tungsten(O), cr-complexes of the type L2M(CO)4 or I,(M(CO)( instead of 7t-complexes <1998EJI1079>. Some derivatives of this heterocycle were also found to display remarkable antibacterial activity <2005BML937>. 

Typical TLC data (silica gel, 6 1 hexanesiethyl acetate) include R - 0.61 (1-acetoxy-1,3-butadiene) 0.51, a red spot [tricarbonyl(cycloheptatriene)chromium] 0.45 a yellow spot (side product that often overlaps with the starting complex) and 0.31 a yellow spot (main intermediate chromium complex). 

Reaction of tricarbonyl(cycloheptatriene)iron 13 with dichlorocarbene resulted in cyclopropanation of the uncomplexed double bond giving cyclopropane 14. Decomplexation failed with trimethylamine oxide, but was successful with copper(II) chloride. 

Tricarbonyl(cycloheptatriene)molybdenum has been prepared by refluxing cycloheptatriene with molybdenum hexacarbonyl in benzene. It is a convenient starting material for the preparation of trisubstituted molybdenum carbonyls and of tropyliummolybdenurn carbonyl salts. ... 

Preparation of bicyclo[3,2,l]oct-2-en-8-one (547 57%) has been achieved by successive treatment of tricarbonyl(cycloheptatriene)iron with tetrafluoroboric acid and sodium borohydride. Similarly, tricarbonyl(cyclo-octatetraene)iron gave bicyclo-[3,3,l]nona-2,6-dien-9-one (62%). Thermolysis of (—)-(548) at 195°C (1 h) gave (— )-(550) by the fast Cope rearrangment of the one-centre epimerization intermediate (549). The alternative two-centre epimerization pathway by way of intermediate... 

The [6 + 3]-cycloaddition between (cycloheptatriene)chromium(O) tricarbonyl 135 and isocyanate or ketene occurs under photo-irradiation conditions, for example, bicyclo[4.2.1]nonane-type adduct 136 was obtained in moderate yield (Equation (22)).237 238... 

In the course of a study of the formation of fluorophosphoranes from chloro-phosphines (22) we observed one exception in the compound chloromethyldi-chlorophosphine, which reacted smoothly with antimony trifluoride to give the flammable fluorophosphine, C1CH2PF2, under conditions where many other chloro-phosphines were invariably converted into fluorophosphoranes. As this fluorophosphine is readily available, its interaction with a metal carbonyl derivative was studied, and cycloheptatriene molybdenum tricarbonyl, obtained from the reaction of molybdenum hexacarbonyl with cycloheptatriene (I, 2), was chosen as a starting compound. 

In an inert atmosphere, excess chloromethyldifluorophosphine was distilled on cycloheptatriene molybdenum tricarbonyl, and the hydrocarbon ligand was readily displaced in a mildly exothermic reaction, requiring a reaction time of as little as 20 to 30 minutes. A high boiling colorless liquid (b.p. 127° at 0.05 mm.) was isolated by distillation, which could be shown to be the expected molybdenum tricarbonyl derivative, formed according to ... 

Complexes of Cr, W, Mo, Fe, Ru, V, Mn and Rh form stable, isolable arene if -complexes. Among them, arene complexes of Cr(CO)3 have high synthetic uses. When benzene is refluxed with Cr(CO)6 in a mixture of dibutyl ether and THF, three coordinated CO molecules are displaced with six-7r-electrons of benzene to form the stable i/fi-benzene chromium tricarbonyl complex (170) which satisfies the 18-electron rule (6 from benzene + 6 from Cr(0) + 6 from 3 CO = 18). Complex formation is facilitated by electron-donating groups on benzene, and no complex of nitrobenzene is formed. Complex formation has a profound effect on reactivity of arenes, and the resulting complexes are used in synthetic reactions. The metal-free reaction products can be isolated easily after decomplexation by mild oxidation using low-valent Cr. Cycloheptatriene also forms a stable complex with Cr(CO)3 and its synthetic applications are discussed below. 

We have thus been able to show that the acetonitrile-pentacarbonyl complexes M(CO)5NCMe (M = Cr, Mo, W) and cycloheptatriene-iron-tricarbonyl C7H3Fe(CO)3 are deprotonated as follows, without attack at the CO ligands (151). 

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