2,4-Dienes are prepared in high yields with high regioselectivity by the codimerisation of acetylenes and alkenes in the presence of a catalytic amount of Ru(cod)(cot) at 80 °C cod = cycloocta-1,5-diene, cot = cycloocta-1,3,5,-triene.
bis(cyclometalated) ruthenium(II) catalyst precursors for CC coupling reactions between alkene and alkyne substrates. The complex [(cod)Ru(3‐methallyl)2] reacts with benzophenone imine or benzophenone in a 1:2 ratio to form bis(cyclometalated) ruthenium(II) complexes (1). The imine‐ligated complex 1 a promoted room‐temperature coupling between acrylic esters and amides with internal alkynes to form 1,3‐diene
描述了一类新的双(环金属化)钌 (II) 催化剂前体的开发,用于烯烃和炔烃底物之间的C C 偶联反应。配合物 [(cod)Ru(3-methallyl) 2 ] 与二苯甲酮亚胺或二苯甲酮以 1:2 的比例反应形成双(环金属化)钌 (II) 配合物 ( 1 )。亚胺连接的配合物1a促进了丙烯酸酯和酰胺与内部炔烃之间的室温偶联,形成 1,3-二烯产物。提议的催化循环包括通过氧化环化、β-氢化物消除和C H 键还原消除形成C C 键。这个 Ru II / Ru IV途径与观察到的1 a 的催化反应性一致,用于温和的尾对尾丙烯酸甲酯二聚反应和通过 [2+2] 降冰片烯/炔环加成形成环丁烯。
Synthesis of 4-Methyldienoates Using a Vinylogous Horner−Wadsworth−Emmons Reagent. Application to the Synthesis of Trichostatic Acid
作者:John T. Markiewicz、Douglas J. Schauer、Joakim Löfstedt、Steven J. Corden、Olaf Wiest、Paul Helquist
DOI:10.1021/jo902422y
日期:2010.3.19
The utility of the unsaturatedphosphonate 1 as a vinylogous Horner−Wadsworth−Emmons reagent was explored in reactions with aldehydes affording 4-methyldienoate esters. Factors that affect E/Z selectivity were studied. A simplified synthesis of trichostatic acid 3 was accomplished to demonstrate utility of this reagent.
Novel aryne Diels-Alderreactions with functionalized acyclic dienes are reported. These give useful cis-substituted dihydronaphthalene building blocks in good yield which are not easily accessible via other means, as demonstrated in the synthesis of sertraline. The first asymmetric aryne cycloaddition with an acyclic diene is also reported, giving excellent diastereoselectivities with Oppolzer's sultam