据报道,由于6-异丙基-(11)和6-异丁基-2 H-苯并[ b ] [1,4]二氧己平-3(4 H)-一(12)而不是预期的海洋气味具有百合味。谷中的香精尽管比基准香精弱,但研究了环丙基环而不是甲基支链对嗅觉性能的影响。6-环丙基-(27),6-(2'-甲基环丙基)-(32)和6-(环丙基甲基)-2 H-苯并[ b ] [1,4]二氧己环-3(4 H)-one(39)由2,3-二甲氧基苯甲醛(22)合成,合成顺序为用(甲氧基甲基)三苯基phosph进行Wittig甲基化/乙基化/同系化,然后进行环丙烷化,脱甲基化,用3-氯-2-(氯甲基)丙-1-烯进行的Williamson醚化和Katsuki-Sharpless氧化。靶结构的气味阈值27,32,和39,它们都是花香-绿百合的最谷添味剂,位于的那个范围铃兰醛(1衍生物),用6-环丙基27作为最有效的(空气0.065 ng / l)。尤其令
Synthesis and Properties of Bimetallic Hoveyda–Grubbs Metathesis Catalysts
摘要:
The catalytic activity of ruthenium Hoveyda-Grubbs complexes in olefin metathesis is a function of complex steric and electronic effects acting on initiation and propagation steps. In order to study the pi-electron factors influencing the initiation process, we attempted syntheses of bimetallic complexes with common organic ligands bearing two chelate rings. While most of the studied ligand exchange reactions of the isomeric bis-chelating benzene derivatives gave mixtures of unstable complexes, a homodinuclear derivative of 1,4-dimethoxy-2,5-divinylbenzene was sparingly soluble and precipitated from the reaction mixture in a pure form. The complex was studied with spectroscopic and X-ray methods, which confirmed the symmetrical bimetallic structure. However, in model metathesis reactions the catalyst displayed activity very comparable to the related monometallic complexes. This suggests that in the bimetallic system two consecutive initiation processes of the metathesis catalyst (first, bimetallic complex + olefin -> monometallic complex + propagating species; second, monometallic complex + olefin -> styrene + propagating species) proceed at similar rates and, thus, no cooperativity between the two steps is displayed. Properties of the family of bimetallic complexes were probed with NMR studies, and pi-electronic effects operating in the systems were discussed.