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Synthesis of aldehydic ribonucleotide and amino acid precursors by photoredox chemistry.

Ritson DJ, Sutherland JD - Angew. Chem. Int. Ed. Engl. (2013)

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Affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.

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In continuing studies aimed at understanding the prebiotic origin of RNA, we recently demonstrated a Kiliani–Fischer-type synthesis of simple sugars from hydrogen cyanide using photoredox cycling of cyanocuprates (Scheme 1)... The photoredox cycle oxidizes to cyanogen and generates associated reducing power in the form of protons and hydrated electrons, which reduce further to formaldehyde imine... Although our previous Kiliani–Fischer-type synthesis started with hydrogen cyanide and proceeded through glycolonitrile, compound itself is probably a more plausible starting point for the synthesis... In the absence of added ammonia, cyanohydrins and produced by rain-in of hydrogen cyanide into the system have the potential to be further reduced in a second stage of photoredox chemistry (Scheme 2)... We had considered the formation of in this way, and envisaged its subsequent reduction as a way of producing glyceraldehyde in the same system as glycolaldehyde, but at a later juncture... However, we had not previously considered the formation and reduction of acetaldehyde cyanohydrin... In the presence of added ammonia, the cyanohydrins produced by rain-in of hydrogen cyanide would be expected to undergo slow conversion to aminonitriles... Addition of and excess ammonia to the system after 4 h of first-stage reduction resulted in the smooth conversion of the aldehydes, , and into the corresponding aminonitriles, , and over a period of days to weeks (Supporting Information)... If the first-stage reduction were to proceed to completion, all of the glycolaldehyde needed to make ribonucleotides and serine (via and ) would instead be converted into acetaldehyde... We found that was the major product after 6 h irradiation thus 2–4 h would seem to be synthetically most productive from a systems perspective... Thus the abiogenesis of the simple sugars required to make RNA appears to be closely related to the abiogenesis of at least four of the proteinogenic amino acids of extant biology... The reductant hydrogen sulfide and the copper(I) cyanide based catalyst could be produced by dissolution of a copper sulfide mineral in cyanide solution, additional being produced by similar dissolution of ferrous sulfide... At this stage we do not attempt to describe a more detailed scenario other than to point out that the RNA and amino acid syntheses could take place in one mixed system or in several closely related systems which then become mixed.

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Photoredox systems chemistry of glycolonitrile 5, with hydrogen sulfide 10 as the ultimate reductant.
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sch02: Photoredox systems chemistry of glycolonitrile 5, with hydrogen sulfide 10 as the ultimate reductant.


Synthesis of aldehydic ribonucleotide and amino acid precursors by photoredox chemistry.

Ritson DJ, Sutherland JD - Angew. Chem. Int. Ed. Engl. (2013)

Photoredox systems chemistry of glycolonitrile 5, with hydrogen sulfide 10 as the ultimate reductant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269183&req=5

sch02: Photoredox systems chemistry of glycolonitrile 5, with hydrogen sulfide 10 as the ultimate reductant.

View Article: PubMed Central - PubMed

Affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

In continuing studies aimed at understanding the prebiotic origin of RNA, we recently demonstrated a Kiliani–Fischer-type synthesis of simple sugars from hydrogen cyanide using photoredox cycling of cyanocuprates (Scheme 1)... The photoredox cycle oxidizes to cyanogen and generates associated reducing power in the form of protons and hydrated electrons, which reduce further to formaldehyde imine... Although our previous Kiliani–Fischer-type synthesis started with hydrogen cyanide and proceeded through glycolonitrile, compound itself is probably a more plausible starting point for the synthesis... In the absence of added ammonia, cyanohydrins and produced by rain-in of hydrogen cyanide into the system have the potential to be further reduced in a second stage of photoredox chemistry (Scheme 2)... We had considered the formation of in this way, and envisaged its subsequent reduction as a way of producing glyceraldehyde in the same system as glycolaldehyde, but at a later juncture... However, we had not previously considered the formation and reduction of acetaldehyde cyanohydrin... In the presence of added ammonia, the cyanohydrins produced by rain-in of hydrogen cyanide would be expected to undergo slow conversion to aminonitriles... Addition of and excess ammonia to the system after 4 h of first-stage reduction resulted in the smooth conversion of the aldehydes, , and into the corresponding aminonitriles, , and over a period of days to weeks (Supporting Information)... If the first-stage reduction were to proceed to completion, all of the glycolaldehyde needed to make ribonucleotides and serine (via and ) would instead be converted into acetaldehyde... We found that was the major product after 6 h irradiation thus 2–4 h would seem to be synthetically most productive from a systems perspective... Thus the abiogenesis of the simple sugars required to make RNA appears to be closely related to the abiogenesis of at least four of the proteinogenic amino acids of extant biology... The reductant hydrogen sulfide and the copper(I) cyanide based catalyst could be produced by dissolution of a copper sulfide mineral in cyanide solution, additional being produced by similar dissolution of ferrous sulfide... At this stage we do not attempt to describe a more detailed scenario other than to point out that the RNA and amino acid syntheses could take place in one mixed system or in several closely related systems which then become mixed.

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