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V. Protonated Heteroaromatics

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    24556
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    Pyranos-1-yl and furanos-1-yl radicals add to protonated hetero­aro­matics to produce C-nuc­leoside derivatives.48–54 A proposed mechanism for this type of reaction is given in Scheme 12.50 Protonation drama­tically increases the rate of addition of a carbon-centered radical to a heteroaromatic compound; in fact, the rate is so fast that it is not necessary to conduct the reaction in an inert atmosphere. Not only does reaction take place in the pres­ence of molecular oxygen but oxygen is a likely participant in the rearomat­ization stage of this process (Scheme 12). In reactions of this type the initially formed radical (R·) usually is generated by photolysis of an O‑ac­yl-N-hy­droxy-2-thiopyridone (eq 15).48 (Reactions of O‑acyl-N-hydroxy-2-thiopyridones are dis­cussed in Chapter 13.)

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    This page titled V. Protonated Heteroaromatics is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Roger W. Binkley and Edith R. Binkley.

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