基于路易斯碱/布朗斯台德酸共催化的均烯丙基酸的硫醇化反应,开发了一种简便制备各种对映体富集的苯硫基取代的内酯的策略。探索了酸控制的区域发散环化(6-endo vs. 5-exo)和苯硫基取代的内酯的酸介导的立体选择性重排。进行了实验和计算研究以阐明区域选择性和对映选择性的起源。计算结果表明,CO和CS键的形成可能会同时发生,而不会形成通常认为的催化剂配位的硫鎓离子中间体,而且底物和SPh之间的潜在π-π堆积是对映确定步骤的重要因素。最后,
by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopperreagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide. Both the organocopperreagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields
Unravelling the olefin cross metathesis on solid support. Factors affecting the reaction outcome
作者:Andrés A. Poeylaut-Palena、Ernesto G. Mata
DOI:10.1039/c004729e
日期:——
Olefin cross metathesis on solid support under a variety of conditions is described. A comprehensive analysis considering diverse factors governing the reaction outcome gives a series of patterns for the application of this useful methodology in organic synthesis. If the intrasite reaction is not possible, homodimerization of the soluble olefin is crucial. When the homodimer is less reactive than its monomer, reaction outcome depends on the homodimerization rate, which, in turn, depends on the precatalyst used and the reaction conditions. If the site–site interaction is a feasible process, the cross metathesis product is obtained exclusively when the newly-formed double bond is resilient to further metathetic events. Taking into account these considerations, we have demonstrated that excellent results in terms of cross metathesis coupling can be obtained under the optimized conditions, and that microwave irradiation is also an interesting alternative for the development of a practical and energy-efficient cross metathesis on solid support.
The present invention relates to the field of perfumery. More particularly, it concerns the use as perfuming ingredients of certain phenol esters of formula
wherein R represents a C
2-6
branched alkyl group or a C
2-6
linear or branched alkenyl group or cyclopropyl containing hydrocarbon group. The present invention concerns also the compositions or articles containing such compounds.
Simple methods for the syntheses of (E)-4- and (E)-5-alkenoic acids by the SN2′ type reactions of γ-vinyl-γ-butyrolactone and δ-vinyl-δ-valerolactone with organocopper reagents