Cyclodimerizations tris phosphite

These cyclodimerization and cyclotrimerization reactions are catalyzed by low valent Ziegler-type Ni catalysts (139—144). Large ligands, such as tris-o-biphenylyl phosphite on nickel tend to favor cydooctadiene (COD) formation while smaller ligands favor the linear dimer, 1,3,7-octatriene. The dimer yield at 80°C and 101.3 kPa (1 atm) is 96%. The nickel catalyst can also be placed on a support so that it can be recycled (145). Many other type catalysts have been reported for this reaction (146). The linear 1,3,7-octatriene and its 1,3,6 isomer are also obtained by a Pd catalyzed dimerization (147—151). The kinetics of thermally induced dimerization to COD has also been studied (152). 

Both bis(l,5-cyclooctadiene)nickel(0) and bis(acrylonitrile)nickel(0) catalyze the polymerization of allene to highly crystalline linear polymers (451). With compounds such as tri-o-tolyl phosphite, bis(acrylo-nitrile)nickel in hydrocarbon catalyzes the cyclodimerization of butadiene to 1,5-cyclooctadiene, whereas in alcohols it catalyzes the... 

Cyclodimerization and Cycloaddition. Tris(l,l,l,3,3,3-hexafluoro-2-propyl)phosphite serves as a ligand in Ni-catalyzed cyclodimerization reactions as well as Rh- or Ni-catalyzed [4-f2] cycloaddition processes. The first example is Ni-catalyzed dimerization of isoprene with tris(l,l,l,3,3,3-hexafluoro-2-propyl) phosphite ligand. The main product is l,4-dimethyl-4-vinyl-cyclohexane (eq 4). 

---