The first microwave-assisted regiospecific synthesis of 6-substituted pterins
The pyrazine ring was developed in a pyrimidine and in a benzene by Isay type condensations under microwave irradiation to afford pterin and quinoxaline systems. Interestingly, the desired isomerically free 6-substituted pterins including pterin sugar derivatives were synthesised in moderate to good yields whereas mixtures of both 6- and 7-isomers (major) are generally obtained using conventional Isay type condensations.
PROTECTION AND DEPROTECTION OF FUSED 2-AMINO-4(3H)PYRIMIDONES: CONVERSION OF PTERINS AND 5-DEAZAPTERINS TO 2,4-DIAMINO DERIVATIVES
5-Deazapterins and pterins are readily converted to their 4-deoxy-4-amino derivatives (a lactam-to-amidine conversion) by reaction with 4-chlorophenyl phosphorodichloridate and 1,2,4-triazole to give intermediate 4- derivatives, followed by reaction with aqueous ammonia.Some anomalous results obtained by application of the Mitsunobu reaction (normally a lactam-to-lactim ether conversion) to 5-deazapterins are detailed.
Taylor, Edward C.,Otiv, S. R.,Durucasu, Inci
p. 1883 - 1895
(2007/10/02)
Model Studies Related to the Cofactor of Oxomolybdoenzymes. Part 4. Reduction of the Pyrazine Ring in Quinoxalines and Pteridines
Reduction of quinoxalines and pteridines with sodium borohydride or sodium cyanoborohydride in the presence of benzyl chloroformate gives N-benzyloxycarbonyl- or N,N'-bisbenzyloxycarbonyl tetrahydro derivatives.
Russell, James R.,Garner, C. David,Joule, John A.
p. 1245 - 1250
(2007/10/02)
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