- Process for N5-formylating tetrahydropteridines
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Intermediates and a process for the synthesis of 6-monosubstituted tetrahydropteridine C6-stereoisomers, including (6S)-tetrahydrofolic acid. The intermediates are shown in their two enantiomeric forms as follows: STR1 wherein R1 and R2/s
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- Synthesis of Tetrahydropteridine C6-Stereoisomers, Including N5-Formyl-(6S)-tetrahydrofolic Acid
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Chiral N1-protected vicinal diamines derived from amino acids were condensed with 2-amino-6-chloro-5-nitro-4(3H)-pyrimidinone, the nitro group reduced, and the amine deprotected.Oxidative cyclization of the resulting triaminopyrimidinone via quinoid pyrimidine intermediates gave a quinoid dihydropteridine, which was then reduced to a tetrahydropteridine C6-stereoisomer.Thus, 6(R)- and 6(S)-propyltetrahydropterin were stereospecifically synthesized (99 percent enantiomeric purity) in good yield from D- and L-norvaline, respectively.Reductive alkylation of (p-aminobenzoyl)-L-glutamate with a niropyrimidine aldehyde derived from D- or L-serine similarly afforded, after cyclization and reduction, (6R)- or (6S)-tetrahydrofolic acid.The latter was then converted to the natural isomer of leucovorin by regioselective N5-formylation with carbonyl diimidazole / formic acid without loss of enantiomeric purity.
- Bailey, Steven W.,Chandrasekaran, Rama Y.,Ayling, June E.
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p. 4470 - 4477
(2007/10/02)
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