• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.244-256
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• 2009

The psoralen-pyrimidine base complexes resulting from interstrand cross-linking through $C_4$-cycloaddition is studied by ab initio and DFT methods. The results indicate that in the case of the molecular complex formation between psoralens and pyrimidine base, the most probable photocycloadditions are 8-MOP< >Thy, Ps< >Cyt and Ps< >Thy. The geometries of photoadducts were optimized at the HF levels and ${\Delta}{G^{\circ}}$ were calculated. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of trans-syn 8-MOP< >Thy, trans-anti Ps(3, 4)< >Cyt, trans-anti Ps(12, 13)< >Cyt, trans-syn Ps(3, 4)< >Thy, trans-syn Ps(12, 13)< >Thy, trans-anti Ps(12, 13)< >Ps(12, 13), cis syn, cis anti Thy< >(3, 4)Ps(12, 13)< >Thy.

• Bulletin of the Korean Chemical Society
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• v.2 no.3
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• pp.112-114
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• 1981

The photocycloaddition reaction of 8-methoxypsoralen with purine and/or pyrimidine bases is studied as a model for the charge transfer interactions of psoralens with DNA bases by the FMO method. The results indicate that, in the case of the molecular complex formation between psoralens and purine and/or pyrimidine bases, the most probable photocycloaddition should occur in the following order: Thy (5,6)<>(3,4) 8-MOP, Cyt(5,6)<>(3,4)8-MOP, Ade (7,8)<>(3,4)8-MOP, Gua(7,8)<>(3,4)8-MOP. The theoretical results for the photocycloaddition reaction are also correlated with the experimental results. The photoadducts between 8-methoxypsoralen and adenine are likely to be C4-cycloadducts through the cycloaddition of 3,4-pyrone double bond of 8-methoxypsoralen to 7,8-double bond of adenine.