Chemical evolution prebiotic synthesis

The term chemical evolution" was introduced by the Nobel Prize winner Melvin Calvin and refers to the process of the synthesis of biochemically important molecules from small molecules and certain chemical elements under the (hypothetical) conditions present on prebiotic Earth. It is assumed that the smaller building block molecules such as amino acids, fatty acids or nucleobases were formed initially, and that these underwent polycondensation to give macromolecules in later stages of development. 

Ferris and Antonucci73 have reported a photochemical synthesis of imidazo[4,5-d]imidazole (80) from 4-aminoimidazole-5-carbonitrile (78), which has attracted interest since 78, and its photochemical precursor diaminomaleonitrile (77) have been proposed74 as key intermediates in the prebiotic chemical evolution of purines. Mechanistic studies7311 suggest that the fused pyrazole 79 may be an intermediate. 

Ferris, J. P, and Hagan, W. J. (1984) HCN and Chemical Evolution The Possible Role of Cyano Compounds in Prebiotic Synthesis, Tetrahedron, 40, 1093-1120. It should be kept in mind that the compounds described in this paper do not have the foundation attached. 

Ferris JP, Hagan J (1984) HCN and chemical evolution the possible role of cyano compounds in prebiotic synthesis. Tetrahedron 40 1093-1125... 

These researchers added carbonate. .. H. J. Cleaves et al. Prebiotic organic synthesis in neutral planetary atmospheres, in Chemical Evolution across Space and Time From the Big Bang to Prebiotic Chemistry, ed. by Zaikowski and Friedrich. 2008, American Chemical Society. Volume 981, Chapter 15, p. 282. DOl 10.1021/ bk-2008-0981.ch015. 

In the probable prebiotic chemical evolution of adenine by pentameriza-tion of hydrogen cyanide, the intermediacy of a dimer of the latter has been assumed although it remains undetected, iminoacetonitrile (119) has been suggested as a plausible structure for the dimer, and the synthesis of iV-t-butyliminoacetonitrile, the first known member of this family, has been reported by a Chicago school (Scheme 44). ... 

Evolution, the process by which systems under non-random selective pressure become more complex, has been a pervasive force over 4.5 billion years of Earth history. Evolutionary episodes, including the prebiotic synthesis of biomolecules, the selection and organization of those molecules into self-replicating systems, the subsequent co-evolution of the geo-and biospheres, and the modern-day acceleration of chemical evolution through human invention, serve to illustrate this recurrent theme. 

The physiologist de Duve concentrated his efforts on a material link between the prebiotic phase of the primeval Earth and the state of development at which RNA (or a similar type of molecule) determined the further progress of the evolution process. In particular, this connecting link needed to have been able to transfer chemical energy, since without such a procedure, the RNA synthesis appears impossible. The molecular species which Christian de Duve favours for this important function is that of the thioesters. The exact reasoning as to why this is the case is discussed in detail in his book Vital Dust Life As a Cosmic Imperative (de Duve, 1996). 

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