Ring opening metathesis synthesis

A drawback to the Durham method for the synthesis of polyacetylene is the necessity of elimination of a relatively large molecule during conversion. This can be overcome by the inclusion of strained rings into the precursor polymer stmcture. This technique was developed in the investigation of the ring-opening metathesis polymerization (ROMP) of benzvalene as shown in equation 3 (31). 

The last decade has witnessed the growing use of olehn metathesis in organic synthesis.Ring closing metathesis RCM, Eq. (6)] and ring opening metathesis [ROM, Eq. (7)1 as well as a combination of these transformations have resulted in providing opportunities to build molecules of interest and importance. 

Lu H, Wang J, Lin Y, Oieng J (2009) One-pot synthesis of brush-like polymers via integrated ring-opening metathesis polymerization and polymerization of amino acid N-carboxyanhy-drides. J Am Oiem Soc 131 13582-13583... 

Controlling the exact architectnre of polymers has always attracted attention in macromolecular chemistry. Snccessfnl synthesis of alternating copolymers nsing ring opening metathesis polymerisation is of great interest also from a mechanistic perspective. NHC ligands were fonnd to be ideal to tune the selectivity of the metathesis initiators. 

Since one of the substrates is a cyclic alkene there is now the possibility of ring-opening metathesis polymerisation (ROMP) occurring which would result in the formation of polymeric products 34 (n >1). Since polymer synthesis is outside the scope of this review, only alkene cross-metathesis reactions resulting in the formation of monomeric cross-coupled products (for example 30) will be discussed here. 

Fig.4A,B. Ring-opening metathesis polymerization (ROMP) A Structures of organometal-lic initiators that have been used in ROMP to generate neobiopolymers. B General pathway for polymer synthesis using ROMP. Molybdenum-initiated reactions are typically capped with aldehydes and ruthenium-initiated with end ethers.

Multiphase homogeneous catalysis (continued) hydroformylation, 42 483-487, 498 hydrogenations, 42 488-491 metal salts as catalysis, 42 482-487 neutral ligands, 42 481 82 organic reactions, 42 495 0X0 synthesis, 42 483-487 ring-opening metathesis polymerization and isomerization, 42 492-494 telomerizations, 42 491-492 diols as catalyst phase, 42 496 fluorinated compounds as catalyst phase, 42 497... 

Scheme 8.1 Synthesis of cross-linked polymer beads via ring-opening metathesis precipitation polymerization. [Mo] = Mo(N-2,6-i-Pr2-...

Efforts towards the synthesis of strained polycyclic hydrocarbons have been described. These compounds are of interest as fuels and fuel additives for advancedpropulsion. Chemistry has been devised for the attachment of azido functionality to the strained hydrocarbon nucleus. Highly unsaturated substituted cubanes have been synthesized. Ring-opening metathesis polymerization of basketene and 2,3-diazabicyclo[2.2.1]hept-2-ene has been studied. 

Bazzi HS, Sleiman HR Adenine-containing block copolymers via ring-opening metathesis polymerization synthesis and self-assembly into rod morphologies. Macromolecules 2002 35 9617-9620. 

Dalphond J, Bazzi H, Kahrim K, Sleiman H. Synthesis and self-assembly of polymers containing dicarboximide groups by living ring-opening metathesis polymerization. Macromol Chem Phys 2002 203 1988-1994. 

Chen B, Metera K, Sleiman HF. Biotin-terminated ruthenium hipyridine ring-opening metathesis polymerization copolymers synthesis and self-assemhly with streptavidin. Macromolecules 2005 38 1084-1090. 

Pontrello JK, Allen MJ, Underbakke ES, Kiessling LL. Solid-phase synthesis of polymers using the ring-opening metathesis polymerization. J Am Chem Soc 2005 127 14536-14537. 

Moore, J. S. Transition Metals in Polymer Synthesis Ring-opening Metathesis Polymerization and Other Transition Metal Polymerization Techniques. In Comprehensive Organometaltic Chemistry // Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Elsevier Oxford, 1995 Vol. 12, pp 1209-1232. 

Kiessling, L. L. Owen, R. M. Synthesis and Applications of Bioactive Polymers Generated by Ring-opening Metathesis Polymerization. 

Ruthenium-catalysed Ring-Opening Metathesis Polymerization (ROMP) 29 526 529 (Equation 10) and Pd(tppms)3-catalysed synthesis of water soluble poly-(p-phenylene) derivatives (Equation ll).530 The latter is a special example of a Suzuki coupling (see earlier). 

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