Non-conjugated diolefins

Mono- olefin Non- conjugated Diolefin Conjugated Diolefin cis -trans trans -trans Non- conjugated Triolefin Con- jugated Triolefin... 

The polymerisation of monocyclic non-conjugated diolefins, which takes place by the double bond opening with simultaneous transannular migration, leads to cyclopolymers having bicyclic repeating units present in the main chain. A typical example of such cyclopolymerisation is the polymerisation of 1,5-cyclooctadiene [31,32] ... 

Scarcely more complicated, in principle, than simple monoolefin complexes are those in which two unconjugated double bonds form independent linkages to a metal atom. Two of the more important complex-forming non-conjugated diolefins are 1,5-cyclooctadiene and norbornadiene, representative complexes of which are shown as (23-1) and (23-11), respectively. An interesting case of three unconjugated double bonds coordinated to one metal atom is shown in (23-III). 

F. Sato, S. Haga, and M. Sato. Synthesis of organoboranes via organoaluminums. A convenient route to trialkenylboranes from non-conjugated diolefins. Chem. Letters, 1978, 999. 

In Table 2 the highest optical yields obtained up to now for different substrates are reported. Relatively good optical yields have been obtained for terminal and for some internal olefins. Similar optical yields are also reported in the hydro-formylation of conjugated diolefins, but in this case asymmetric induction seems to occur in the hydrogenation of the non-ehiral unsaturated aldehyde which is the primary reaction product27). 

Coordination polymerisation via re complexes comprises polymerisation and copolymerisation processes with transition metal-based catalysts of unsaturated hydrocarbon monomers such as olefins [11-19], vinylaromatic monomers such as styrene [13, 20, 21], conjugated dienes [22-29], cycloolefins [30-39] and alkynes [39-45]. The coordination polymerisation of olefins concerns mostly ethylene, propylene and higher a-olefins [46], although polymerisation of cumulated diolefins (allenes) [47, 48], isomerisation 2, co-polymerisation of a-olefins [49], isomerisation 1,2-polymerisation of /i-olcfins [50, 51] and cyclopolymerisation of non-conjugated a, eo-diolefins [52, 53] are also included among coordination polymerisations involving re complex formation. 

Finally, despite the plethora of reports providing evidence for the one carbene exchange mechanism, in certain circumstances cyclobutanes can be converted quantitatively into diolefins and, of greater importance, two non-conjugated olefinic groups (31) can be converted into a cyclobutane (32) almost quantitatively by the methathesis catalyst PhWCls-AlCla. This suggests that the carbene mechanism is not a unique pathway for olefin disproportionation and that in some circumstances cyclobutane intermediates may be formed. 

Dave Frey, undertook the polymerization of non-conJugated acetylenes, since the cyclopolymerization would leave unsaturation in the ch dn and provide functional handles for the degradation (ozonolysis) and ultimately identification of the polymer structure by identification of the fragments. A number of examples of cyclopolymerization and cyclocopolymerization of diolefins were added to the growing list . 

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