Norbornadiene dimer

The distillation residues are combined and distilled (b.p. 70 73°/0.5 mm.), giving 326 g. (70% yield) of norbornadiene dimer. The pot residue solidifies when cooled to room temperature and crystallization from 95% ethanol gives 24.5 g. (5.3%) of norbornadiene trimer, m.p. 176-178°. 

Norbornadiene dimer is a colorless liquid consisting of a mixture of isomers (1, 84%), (2, 12%), and (3, 4%). They can be separated by distillation through an annular Teflon spinning band column manufactured by Nester/Faust Corporation, Newark,... 

Examples of the catalytic C-C bond-cleavage reaction by Ru(0) complex are limited, though some examples have been reported. Under mild conditions, Ru(l,5-COD)(l,3,5-COT) catalyzes the conversion of 2,5-norbornadiene to a cage-shaped compound pentacyclo[6.6.0.0 .0. 0 ° ]tetradeca-4,ll-diene. In this reaction, two norbornadienes dimerize, and at least two C-C bond cleavage reactions are involved to give the product, though the details of the mechanism are not clear (Scheme 14.18) [46]. 

The catalysts found active in the norbornadiene dimerization are various nickel tt complexes, among them Ni(CO)4, Ni(CH2=CHCN)2, Ni(0) complexes of 1,1-dicyanoethylenes, and the corresponding phosphine substitution or addition compounds (3, 32, 33, 47). Other active catalysts are Co2(CO)8, Fe2(CO)9, Co2(CO)g 2P(CgH5)3, Co(CO)3NO, and Fe(CO)2(NO)2 (3, 4, 32, 33, 44, 48). Efficient catalysts were also obtained by the in situ reduction of Ni, Co, or Fe chelates with organo-aluminum compounds (46, 49). Finally, dimerization of norbornadiene could also be effected with Rh on carbon (45). The nickel catalysts... 

Uganda compete with norbornadiene for metal coordination sites. If present in low concentration norbornadiene dimerization may occur via the intermediates (XLIV-XLVI). High concentration of the ligands causes inhibition. 

A trimer of norbornadiene, m.p. 201°, was obtained from the reaction of the olefin with Ni[P(CaH5)3]4 as the catalyst 58). Except that it is unsaturated, no further structural information is presently available on this hydrocarbon. Rhodium on carbon also catalyzes norbornadiene dimerization and trimerization (45). Three dimers, (XXIII), (XXIX), and (XXX) or (XXXI) are formed in the ratio of 4 84 12, in 70-80% yield at 90% conversion (45). In addition, 20-30% of a crystalline trimer, m.p. 67-68°, was isolated. On the basis of NMR and IR measurements it could have either structure (LIV) or (LV). 

C2H4 Self-homologation Olefin metathesis Norbornadiene dimerization... 

Similarly, butadiene and ethylene can react together in the presence of naked nickel or nickel-ligand catalytic systems to give c/j,/ra 5-l,5-cyclo-decadiene in yields up to 80% [Eq. (86) (Wilke, 1963 Heimbach and Wilke, 1969)]. Norbornadiene dimerizes or reacts specifically with olefins using Ni(0) (Schrauzer and Glockner, 1964 Schrauzer et al., 1970). 

C27H38O, Isophorone condensation trienone, 43B, 256 C28H20f Di-p-anthracene, 31B, 112 46B, 192 C28H26Br04, Norbornadiene dimer di-p-bromobenzoate, 38B, 242 C28H28 f 9,10-Benzotricyclo[3.3.2.0 ]deca-3(7),9(10)-diene dimer, 43B, 256... 

Ci4Hi6AgN03, Norbornadiene dimer - silver nitrate, 42B, 699 Cl4H16M0O3, (1-6-T -7-t-Butyl-cycloheptatriene)(tricarbonyl)molybden-um(0), 41B, 922... 

The norbornadiene dimer exo-trans-exo-pentacyc ote-tradeca-5,11-diene has been employed as a crosslinking agent for the controlled synthesis of these star-shaped copolymers in the catalytic presence of W(CHr-Bu)(NAr)(0/-Bu)2 or Mo(CHr-Bu)(NAr)Or-Bu)2 [66], Star polymers in which the arms are block copolymers of different polarities can be prepared by this method, as well as star polymers in which the composition of the arms is different, as are the solubility characteristics and stereochemical regularity. Heterostars thus obtained, in which the number of the different arms will be approximately equal, may exhibit interesting intramolecular phase separations. 

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