Trost Barry M, Shen Hong C, Horne Daniel B, Toste F Dean, Steinmetz Bernhard G, Koradin Christopher
Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
Chemistry. 2005 Apr 8;11(8):2577-90. doi: 10.1002/chem.200401065.
The Ru-catalyzed intramolecular [5+2] cycloaddition of cyclopropylenynes is investigated with respect to the regio- and diastereoselectivity as well as the functional group compatibility of the reaction. Evidence for the mechanism as occurring through a ruthenacyclopentene intermediate is elucidated from 1) the study of the diastereoselectivity of the cycloaddition; 2) the effect of variation of substituents on the regioselectivity of cyclopropyl bond cleavage in 1,2-trans- and 1,2-cis-disubstituted cyclopropanes and 3) examples that clearly do not involve ruthenacyclohexene as intermediates as products still incorporate the cyclopropyl moiety. The scope and limitations of the Ru-catalyzed cycloaddition are discussed and compared with the Rh-catalyzed reaction. The potential power of this methodology towards natural product total synthesis is demonstrated by the formation of several polycyclic systems with the chosen reaction conditions and readily available cyclopropylenyne substrates.
对钌催化的环丙炔烯分子内[5+2]环加成反应的区域选择性、非对映选择性以及反应的官能团兼容性进行了研究。通过以下方面阐明了反应机理是通过钌环戊烯中间体发生的证据：1）环加成反应非对映选择性的研究；2）1,2-反式和顺式二取代环丙烷中取代基变化对环丙基键断裂区域选择性的影响；3）明确不涉及钌环己烯作为中间体的例子，因为产物仍包含环丙基部分。讨论了钌催化环加成反应的适用范围和局限性，并与铑催化反应进行了比较。通过在选定的反应条件下使用易于获得的环丙炔烯底物形成几个多环体系，证明了该方法在天然产物全合成方面的潜在能力。
