1,3-Cyclopentadiene 1,2,3,4,5-pentamethyl

An analogous stepwise mechanism was also proposed by Wohrle [36] for the cation-radical-initiated cycloaddition of electron-rich allenes with pentamethyl-cyclopentadiene in the presence of tris (p-tolyl) aminium hexafluoroantimonate (TTA SbF6 ) (Equation 1.15). 

As mentioned earlier, ruthenium cymene, rhodium and iridium pentamethyl-cyclopentadiene are good metal complexes, to start with, in a screen. It is diffi-... 

Hetero Diels-Alder reactions are very useful for constructing heterocyclic compounds, and many important chiral molecules have thus been synthesized. Although the retro Diels-Alder reaction does not itself involve the asymmetric formation of chiral centers, this reaction can still be used as an important tool in organic synthesis, especially in the synthesis of some thermodynamically less stable compounds. The temporarily formed Diels-Alder adduct can be considered as a protected active olefin moiety. Cyclopentadiene dimer was initially used, but it proved difficult to carry out the pyrrolytic process. Pentamethyl cyclopentadiene was then used, and it was found that a retro Diels-Alder reaction could easily be carried out under mild conditions. 

The oxidative addition reaction of [Ru6C(CO)ifJ2 4 and pentamethyl-cyclopentadiene in the presence of [Fefrj-CsHs)]4 in dichloromethane at room temperature affords HRufiC(CO)l4(i7-CsMe5) 105 in 10% yield together with larger quantities of the homoleptic cluster Ru6C(CO)17 2.29... 

Neodymium cyclopentadienyl complexes are also obtained in-situ by the addition of Cp-derivatives (e.g. indene, cyclopentadiene, pentamethyl-cyclopentadiene, tetramethylcyclopentadiene, di-tert-butylcyclopentadiene, methylcyclopentadiene and fluorene) to standard Nd-catalyst systems such as NdV/MAO. It can be assumed that the respective cyclopentadienyl-anions are formed by proton abstraction from the Cp-derivatives. In the homopolymerization of BD the addition of Cp-derivatives results in an increase of the 1,2-content of about 4-10%. In addition, the in-situ formed Nd Cp-derivatives... 

The pentamethyl cyclopentadiene lanthanide complexes containing hydrocarbyl substituents have been studied extensively for their applications in homogeneous catalysis and C-H activation. The well-known catalyst of the Ziegler-Nutta type Cp2LnMe(Et20) is typical of the large number of compounds [155] that have been studied. Solvent-free electrophilic alkyl derivatives serve as precursors of the majority of the compounds which have been studied. 

From the [8 + 2] cycloaddition of 8-methoxyheptafulvene to C70, the same group isolated a chiral isomer for which they proposed a C(l)-C(2) adduct structure (C7o-analogue of ( )-230 cf. Scheme 1.22).246 The same regioiso-mer was identified by Taylor and co-workers as the main product of the [4 + 2] cycloaddition of pentamethyl cyclopentadiene to C70.447 A C -symmetric Diels-Alder adduct is, finally, expected from the reaction of C70 with 2-[(ferrocenyl)methylene]-3-methylenequinuclidine.448... 

Although the majority of studies reported over recent years concerning water activation by synthetic metal complexes have focused on systems of biological relevance, advances have also been made in understanding the water binding and activation properties of organometaiiic complexes. For example, several transition metal aqua complexes that feature only t-cyclic [e.g. // -arene, -cyclopenta-diene (Cp), pentamethyl-// -cyclopentadiene (Cp )] or carbonyl ligands have been recently reported [65-74]. 

Pentamethylcyclopentadienyl-bis(thiolatothiatriazyl)rhodium, 3528 f l,2,3,4,5-Pentamethyl-2,4-cyclopentadien-l-yllithium, see Pentamethylcyclopentadienyllithium, 3327... 

SYNS a,P-CYCLOPENTAMETHYLENETETRAZOLE PENTAMETHYLENETETRAZOL PENTAMETHYL-ENE-l,5-TETRAZOLE PENTYLENETETRAZOL 6,7,8,9-TETRAHYDRO-5-AZEPOTETRAZOLE 6,7,8,9-TETRAHYDRO-5H-TETRAZOLOAZEPINE 7,8,9,10-TETRAZABICYCLO(5.3.0)-8,10-DECADIENE 1,2,3,3A-TETRAZACYCLOHEPTA-8A,2-CYCLOPENTADIENE... 

---