Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, USA.
J Am Chem Soc. 2010 Jul 14;132(27):9335-40. doi: 10.1021/ja1009162.
The regioselectivity and stereoselectivity aspects of the Diels-Alder/radical hydrodenitration reaction sequence leading to trans-fused ring systems have been investigated with density functional calculations. A continuum of transition structures representing Diels-Alder and hetero-Diels-Alder cycloadditions as well as a sigmatropic rearrangement have been located, and they all lie very close in energy on the potential energy surface. All three pathways are found to be important in the formation of the Diels-Alder adduct. Reported regioselectivities are reproduced by the calculations. The stereoselectivity of radical hydrodenitration of the cis-Diels-Alder adduct is found to be related to the relative conformational stabilities of bicyclic radical intermediates. Overall, the computations provide understanding of the regioselectivities and stereoselectivities of the trans-Diels-Alder paradigm.
通过密度泛函计算研究了导致反式稠合环体系的 Diels-Alder/自由基加氢脱氮反应序列的区域选择性和立体选择性方面。已经定位了一系列代表 Diels-Alder 和杂 Diels-Alder 环加成以及 sigma 重排的连续过渡态,它们在势能面上的能量非常接近。所有三条途径在 Diels-Alder 加合物的形成中都很重要。计算再现了报道的区域选择性。发现顺式 Diels-Alder 加合物的自由基加氢脱氮的立体选择性与双环自由基中间体的相对构象稳定性有关。总体而言,计算为反式 Diels-Alder 范例的区域选择性和立体选择性提供了理解。