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Synthesis of Cyclobutane Analogue 4: Preparation of Purine and Pyrimidine Carbocyclic Nucleoside Derivatives.


ABSTRACT: The coupling of 2-bromo-3-benzoyloxycyclobutanone with purine under basic conditions produces two regioisomers consisting of the N-7 and N-9 alkylated products in equal amounts in their racemic forms. The distribution of the isomers is consistent with the charge delocalization between the N-7 and N-9 positions of the purinyl anion. The structural assignments and relative stereochemistry of each regioisomer were based on 1 and 2D NMR techniques. The relative stereochemistry of the C-2 and C-3 substituents in each regioisomer was the trans orientation consistent with steric factors in the coupling step. The N-9 regioisomer was reduced with sodium borohydride to give the all trans cyclobutanol as the major product in a stereoselective manner. The alcohol was debenzoylated with sodium methoxide in a transesterification step to give the nucleoside analogue. The regioisomeric pyrimidine nucleosides were prepared by Vorbrüggen coupling of the 3-hydroxymethylcyclobutanone triflate with either thymine or uracil followed by stereoselective hydride addition. Regiospecificity of the coupling at the N-1 position was observed and stereoselective reduction to the trans-disubstituted cyclobutanol structure assignments was based on NMR data.

SUBMITTER: Hasaneen N 

PROVIDER: S-EPMC6767184 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Synthesis of Cyclobutane Analogue 4: Preparation of Purine and Pyrimidine Carbocyclic Nucleoside Derivatives.

Hasaneen Noha N   Ebead Abdelaziz A   Hassan Murtaza M   Afifi Hanan H   Hunter Howard H   Lee-Ruff Edward E   El-Gohary Nadia S NS   Maarouf Azza R AR   El-Emam Ali A AA  

Molecules (Basel, Switzerland) 20190905 18


The coupling of 2-bromo-3-benzoyloxycyclobutanone with purine under basic conditions produces two regioisomers consisting of the <i>N-7</i> and <i>N-9</i> alkylated products in equal amounts in their racemic forms. The distribution of the isomers is consistent with the charge delocalization between the <i>N-7</i> and <i>N-9</i> positions of the purinyl anion. The structural assignments and relative stereochemistry of each regioisomer were based on 1 and 2D NMR techniques. The relative stereochem  ...[more]

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