2-dicarbonyl-2- manganese

Photolysis of n5 2,4-dimethylpentadien-l-yl manganese tricarbonyl [Mn(Tl5-2,4-Mc2C5H5)(CO)3] has been reported 59 to afford the THF adduct [Mn(T 5-2,4-Me2C5H5)(CO)2(THF)], which on reaction with butynedioic acid dimethyl ester and diphenylacetylene afforded respectively T 5-l,2-dimethoxycarbonyl-4,6-dimethylcyclohepta-2,4-dien-l-yl manganese tricarbonyl (39) and Ti5-4,6-dimethyl-l,2-diphenylcyclohepta-2,4-dien-l-yl manganese tricarbonyl (40) in formal [5 + 2] cycloaddition reactions. Propynoic acid methyl ester formed the 2 1 adduct T 5 2-i,3.dimethyl-6-methoxycarbonyl-6-( -2 -methoxycarbonylvinyl)-cyclohepta-2,4-dien-l-yl manganese dicarbonyl (41) which was characterised by X-ray diffraction. 

Barbeau, C., Dichmann, K. S. Ricard, L. (1973) Structure cristalline et moleculaire du cyclopentadienyle dicarbonyle tri-phenylphosphine manganese, MnCsHsfCO P gHsta, Can. J. Chem 51,3027-3031. 

The low yield in this reaction might be caused by a number of reasons. First, the overall reaction is only rapid for readily enolizable compounds. 1,3-Dicarbonyl compounds will therefore be a better choice as compared to acetic acid. Second, to prevent oxidation of radical 54, it is advantageous to work with excess diene and therefore speed up trapping of 54 through diene addition. Finally, lactone 55 can, as an enolizable compound itself, also be oxidized by manganese(III) acetate and form various oxidation products. Shorter reaction time and the use of understoichiometric amounts of oxidant might therefore benefit the overall result. All these factors have been taken into account in the synthesis of bicyclic /-lactone 56, which has been obtained from cyanoacetic acid and 1,3-cyclohexadiene in 78% yield within 15 min reaction time (equation 25)60,88. 

One of the most common approaches to pyrazine ring construction is the condensation of diaminoethane and 1,2-dicarbonyI compounds such as 206 to provide pyrazines 207 after aromatization. Aromatization was accomplished by treating the dihydropyrazines with manganese dioxide in the presence of potassium hydroxide <00JCS(P1)381>. The N-protected 1,2-dicarbonyl compounds 206 were prepared from L-amino acids by initial conversion into diazoketones followed by oxidation to the glyoxal. 

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

The reactions between cyclopropenes and carbon monoxide in the presence of transition metals have been of some use in synthesis,93 and in 1978 Binger initiated a study of the reactions between metal carbonyls and cyclopropenes in order to elucidate the generality of these reactions.75 It was found that dicarbonyl 775-cyclopentadienyl(tetrahydrofuran)manganese(I) reacted with 3,3-dime thy Icy clopropene at 0°C to produce -(vinylketene) complex 81 in fair yield. The only other transition metal in Binger s study that was found to react with 3,3-dimethylcyclopropene in this manner was iron (see Section VI,B). 

As has been deseribed, the parent monoearbollide-metal earbonyl piano-stool species [2-(CO) -c/oi o-2,l-MCBioHii] are now known for all of the metals M = Mo (12), W (13), Re (14), Fe (11), Ru (6), Os (8), and Ni (18). Evidence also exists for a diearbonyl-platinum analogue of eompound 18, ° and as mentioned earlier, the manganese analogue of 14 has also briefly been reported. A notable absenee from this list, however, is any representative of the Group 9 metals. The earbonyl nitrosyl-cobalt complex 21 is very elosely related to the hitherto unknown dicarbonyl-cobalt dianion [2,2-(CO)2-c/oi o-2,l-CoCBioHii] and this species remains an attractive synthetie target. 

F,SCH, Methanesulfonic acid, trifluoro-iridium, manganese and rhenium complexes, 26 114, 115, 120 platinum complex, 26 126 OiFeCgH, Iron, acetyl dicarbonyl (if -cyclopentadienyl)-, 26 239 0,FeN2C2 Hll(, Iron, tricarbonylbis(2-isocy-ano-l,3-dimethylbenzene)-, 26 54 0.iMoNaCHH5-2 C4H ,02, Molybdate 1 -), tricarbonyl(T) -cyclopentadienyl)-sodium, compd. with 1,2-dimethoxy-ethane-(l 2), 26 343 0,NaWC H5-2 C4H ,02, Tungstate(l -), tricarbonyl(ris-cyclopentadienyl)-... 

Fig. 5. MO diagram of M-methylenebis[dicarbonyl(Tj5-cycIopentadienyI)manganese] (Mn— Mn) (3a) according to Lichtenberger et al. (209).

The 77-cyclopentadienyliron dicarbonyl dimer and the mixed metal carbonyl 7r-cyclopentadienyliron-manganese heptacarbonyl are protonated by strong acids to form isolatable salts, namely [CpFe(CO)2]2H +PF6 and [CpFeMn(CO)7H]+PF6 . The ruthenium dimer [CpRu(CO)2]2 behaves similarly, although no salt was isolated (63). 

Hwu et al. have examined the dependence of the metal oxidant on the mode of reactivity in silicon-controlled allylation of 1,3-dioxo compounds [95JOC856]. The use of manganese(III) acetate furnished the dihydrofuran product 22 only. On the other hand, use of cerium(IV) nitrate resulted in the formation of both acyclic (23) as well as the cyclized compound, with the product distribution dependent on the nature of the allylsilane. Facile synthesis of dihydrofurans by the cerium(IV) mediated oxidative addition of 1,3-dicarbonyl compounds to cyclic and acyclic alkenes has also been reported [95JCS(P1)187]. 

Cat13 = dicarbonyl-cyclopentadienyl-triphenylphosphine(trichloro-tin(IV))-manganese(in) ... 

Manganese acetate-promoted oxidative addition of 1,3-dicarbonyl compounds (351) to endo-cyclic enol ethers (352) and enol lactones (353) gives 2,3,3a,6a-tetrahydrofuro[2,3-6]furan derivatives (354) and (355) <87CL223, 91TL711, 91TL7107). 

The anionic complex, in which three dicarbonyl(cyclopentadienyl)manganese groups are connected by a bridging methanetellurolate ligand, was obtained from the corresponding /r3-tcllurido compound and methyl lithium. 

H. Berke, Simple Synthesis of Dicarbonyl(p-cyclopentadienyl)(3,3-di-ieri-butylallenyli-dene)manganese, Angew. Chem. Int. Ed. Engl. 15, 624 (1976). 

Manganese(m)-mediated oxidative annulation of methylenecyclopropanes with 1,3-dicarbonyl compounds produces spirocyclopropane 2,3-dihydrofuran derivatives in moderate to good yields under mild conditions (Equation 63) <2005JOC3859>. 

The imique reactivity of methylenecyclopropanes prompted Zhou to test on this substrate the manganese (Ill)-mediated free radical cychzation of alkenes with 1,3-dicarbonyl compoimds [149]. It was found that benzyh-... 

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