Peyrane F, Denhez C, Guillaume D, Clivio P. Anti Regiospecificity in the Photosensitized Cycloaddition of 4-Tetrazolouracil Nucleoside
†.
Photochem Photobiol 2021;
98:640-648. [PMID:
34655494 DOI:
10.1111/php.13541]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/12/2021] [Indexed: 11/29/2022]
Abstract
The [2 + 2] photocycloaddition of natural pyrimidine nucleobases is devoid of regioselectivity. Although modified pyrimidines have been developed to selectively obtain syn-cyclobutane isomers, the targeted formation of anti-cyclobutane isomers has not been addressed yet. Herein, using NMR analyses and DFT calculations, we demonstrate that the acetone photosensitized excitation of the 4-tetrazolouracil motif in the nucleoside series specifically provides anti-cyclobutane photoproducts in 51% yield. In addition, the cis stereomer formation is preferred over the trans-cyclobutane formation (71:29).
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