Ring-opening metathesis polymerization carbene synthesis

Remarkable development over the last 10-15 years in the synthesis of well-defined functional-group-tolerant ruthenium carbenes (Grubbs-related catalysts) also caused real development of the metathesis-based reactions in organosilicon polymers. For recent reviews on metathesis of organosilicon compounds see Refs. [6,7]. Unsaturated organosilicon polymers can be synthesized via ruthenium carbene catalyzed ring-opening metathesis polymerization (ROMP) of silylsubstituted cycloalkenes (Eq. 113). 

Metal-carbene complexes undergo numerous reactions, several of which are useful in the synthesis of complex organic molecules. These complexes are also intermediates in processes such as metathesis and ring-opening metathesis polymerization (Chapter 11). In Chapter 10 we will discuss the structure, synthesis, and... 

It is still unclear how the initiation step in alkene metathesis occurs and how the initial carbene forms. Commercial applications of metathesis include the triolefin process, in which propylene is converted to ethylene and butene, the neohexene process, in which the dimer of isobutylene, Me3CCH=CMe2, is metathesized with ethylene to give Me3CCH=CH2, an intermediate in the manufacture of synthetic musk, and a 1,5-hexadiene synthesis from 1,5-cy-clooctadiene and ethylene. Two other applications, SHOP and ROMP (Shell higher olefins process and ring-opening metathesis polymerization), are discussed in the next section. 

The reversible nature of the metathesis reaction can lead to ROM reaction of endocyclic olefins under the thermodynamically favored conditions. The self-metathesis process of the ring-opened carbene intermediate, which brings about a polymerization (ROMP), is generally used as the preparation of polymers (Scheme 24.28). On the other hand, the combined process of ROM with the other metathesis is very useful for the synthesis of a monomeric molecule. In contrast to normal RCM and CM reactions, in... 

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