Trimethylenemethane complex

Zeolite frameworks, 29, 103 Zirconacarboranes, 306 Zirconium diazametallacycles, 252-255 Zirconium f/ -styrene complexes, 255 Zirconium trimethylenemethane complexes, 256-257... 

Scheme 21. The gas-phrase reactions of CoO+ with 2-methylpropane (iso-butane). Note that the compound labeled A is a 2-methyl-l-propene (iso-butylene) complex of Co , while the compound labeled B is a trimethylenemethane complex of Co. ...

The reaction of methylenecyclopropanes with transition metal complexes is well known to promote a catalytic a-ir cycloaddition reaction with unsaturated compounds, in which a trimethylenemethane complex might exist71-76. Recently, much interest has been focused on the interaction of strained silicon-carbon bonds with transition metal complexes. In particular, the reaction of siliranes with acetylene in the presence of transition metal catalysts was extensively investigated by Seyferth s and Ishikawa s groups77-79. In the course of our studies on alkylidenesilirane, we found that palladium catalyzed reaction of Z-79 and E-79 with unsaturated compounds displayed ring expansion reaction modes that depend on the (Z) and (E) regiochemistry of 79 as well as the... 

In trimethylenemethane complexes, the metal stabilizes an unusual and highly reactive ligand which cannot be obtained in free form. Trimethylenemethanetricar-bonyliron (R=H) was the first complex of this kind described in 1966 by Emerson and coworkers (Figure 1.2) [38]. It can be obtained by reaction of bromomethallyl alcohol with Fe(CO)5. Trimethylenemethaneiron complexes have been applied for [3+2]-cycloaddition reactions with alkenes [39]. 

In a variation on the two-component cycloaddition reaction, a [3+3] strategy was reported whereby reaction of enantiomerically pure aziridines, generated from amino acids, with palladium trimethylenemethane complexes leads to a piperidine (Scheme 114). Yields ranged from 63% to 82% and the efficiency of the methodology was demonstrated by the four-step synthesis of (—)-pseudoconhydrin <2001SL1596>. 

Cross-conjugated dienyltricarbonyliron cations have been prepared as follows from trimethylenemethane complexes [Eq. (22)] (186,187) ... 

Substituted trimethylenemethane complexes can be prepared from the appropriate reagents. In general, any substituents on the trimethylenemethane group direct the attached carbon to the /3-carbon of the acceptor alkene (equation 90). This directing effect is seen for both electron-donating and electron-withdrawing substituents. 

The trimethylenemethane complexes XLII and XLIII arise from dimerization. The parent 7f-allyl complex, XLIV, can be readily prepared from 3-chloro-2-(chloromethyl)-propene and Na tetracarbonylferrate - . Trimethylenemethane complexes of Mo and Cr are similarly prepared in low yield . ... 

ArCH2COCH2Ar with the unstable a-derivative being possible intermediates. Naphthalene, a more flexible system, reacts in a rather surprising manner so that j8-methylnaphthalene yields the trimethylenemethane complex (XXI) (438). 

First, cis- and trans-2-phenylmethylenecyclopropanes-3-d were shown to give trimethyl-enemethane complexes with the deuterium at a location consistent only with disrotatory ring-opening (Figure 41). Second, reaction of 2,2-diphenylmethylenecyclopropane with a variety of iron carbonyl reagents allowed isolation of the methylenecyclopropane iron tetracarbonyl complex. This compound could be shown to give the trimethylenemethane complex on reaction with trimethylamine-N-oxide or diiron nonacarbonyl, both of which... 

JOM(322)103>. Other more exotic addition reactions of (55) have also appeared including reactions with allenes <90OM289> and phosphinimines <89JA7279,920M2613). The former reaction is an efficient method for the preparation of iron trimethylenemethane complexes. 

Ring-opening between C(2) and C(3) to give trimethylenemethane complexes III 153, i54) jn SQme cases the intermediacy of I could be proven 153). 

A number of investigations have appeared documenting the metal-mediated cleavage of a variety of cyclopropane derivatives, particularly those which are more reactive than ordinary cyclopropanes due to additional structural strain, unsaturation and/or substituents. In a pioneering study, methylene cyclopropane was shown to react with Fe2(CO)9 to furnish trimethylenemethane complex 6 [15]. 

Except for the trimethylenemethane complex, complexes of the types shown in Figure 4.8 can be treated as arachno mixed metal-carbon MC clusters, formally containing (n -1- 4) skeletal bond pairs to hold their (n + 1) skeletal atoms together. ... 

Compared to the f7 -allyl complexes of Pd(ll) and Pt(ll), the r/ -propargyl analogs were much more prone to accept the central attack of the nucleophile [74]. A metallacyclobutene complex formed then underwent either 1,3-hydrogen shift to give trimethylenemethane complex or further addition of proton to give substituted )7 -allyl complexes (Scheme 8.44). The central carbon of r -propargyl complex of Pt was more reactive to nucleophile than that of Pd [75]. This order of the reactivity at central carbon (Pt > Pd) is the same as that of the stability... 

Trimethylsilylmethyl)allyl acetate (263) is a useful compound, which generates Pd-trimethylenemethane complex (TTM) 264 and undergoes [3 -I- 2] cycloadditions with 265 to afford 266. Also [3 + 3] cycloaddition is possible [97]. The carbonate 267 can be used for similar cycloadditions under neutral conditions [98]. 

The analysis of the diagram representing the interaction of Fe(CO)3 with 1,3-butadiene leads to the conclusion that conformation (8.2) of Fe(C4H6)(CO)3 is the most stable (Figure 8.3). Experiments show that in the case of trimethylenemethane complexes of the type Fe(tmm)(CO)3 (tmm = trimethylenemethane and its derivatives). 

Table 8.2. Structures of Metal Diene, Cyclobutadiene, and Trimethylenemethane Complexes...

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