Cyclopentene living systems

The authors chose pyruvic acid as their model compound this C3 molecule plays a central role in the metabolism of living cells. It was recently synthesized for the first time under hydrothermal conditions (Cody et al., 2000). Hazen and Deamer carried out their experiments at pressures and temperatures similar to those in hydrothermal systems (but not chosen to simulate such systems). The non-enzymatic reactions, which took place in relatively concentrated aqueous solutions, were intended to identify the subsequent self-selection and self-organisation potential of prebiotic molecular species. A considerable series of complex organic molecules was tentatively identified, such as methoxy- or methyl-substituted methyl benzoates or 2, 3, 4-trimethyl-2-cyclopenten-l-one, to name only a few. In particular, polymerisation products of pyruvic acid, and products of consecutive reactions such as decarboxylation and cycloaddition, were observed the expected tar fraction was not found, but water-soluble components were found as well as a chloroform-soluble fraction. The latter showed similarities to chloroform-soluble compounds from the Murchison carbonaceous chondrite (Hazen and Deamer, 2007). 

Another clear example of an equilibrium metathesis reaction is the ROMP of cyclopentene initiated by the tungsten analogue of 2. The reaction may be totally reversed by placing the system under vacuum thereby stripping off the monomer units from the living metal carbene complexes (Schrock 1989). 

Cyclopentene-norbornene block copolymers have been prepared with the living tungsten-carbene system (W(CHt-Bu)(NAr)(Ot-Bu)2, but the structure of this product has not been studied in detail [54]. Because there is a marked difference in the reactivity of the two monomers, rigorous reaction conditions must be applied to obtain the virtual block copolymer (76). 

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