Sodium nitrite (NaNO2) catalysed iodo-cyclisation of alkenes and alkynes using molecular oxygen
摘要:
We have developed a convenient iodo-cyclisation reaction using NaNO(2) as catalyst and molecular oxygen as the terminal oxidant. The reactive species, acetyl hypoiodite (IOAc), was generated in situ from TBAI and AcOH. The iodo-cyclisation reaction with a range of alkenes and alkynes gave good to excellent yields. Iodo-amination products can also be obtained using carbarnates prepared from commercially available allylic alcohols and alkynic alcohols. (c) 2008 Elsevier Ltd. All rights reserved.
Ti-direct, powerful, stereoselective aldol-type additions of esters and thioesters to carbonyl compounds: application to the synthesis and evaluation of lactone analogs of jasmone perfumes
thiophenyl esters or thioaryl esters with aldehydes and ketones was performed (total 46 examples). The present method is advantageous from atom-economical and cost-effective viewpoints; good to excellent yields, moderate to good syn-selectivity, substrate variations, reagent availability, and simple procedures. Utilizing the present reaction as the key step, an efficient short synthesis of three lactone
A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Brønsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies
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,
Oxidation of alcohols by electrochemically regenerated nickel oxide hydroxide. Selective oxidation of hydroxysteroids
作者:Johannes Kaulen、Hans-J. Schäfer
DOI:10.1016/0040-4020(82)80110-5
日期:1982.1
Primary alcohols, α,ω-diols and secondary alcohols are easily transformed into carboxylic acids, dicarboxylic acids or ketones, respectively, by heterogeneous oxidation with nickel oxide hydroxide electrochemically regenerated at a nickel hydroxyde electrode. The results are discussed in comparison to those of the nickel peroxide and chromicacidoxidation. The oxidation rate decreases with increasing
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
Synthesis of Secondary Unsaturated Lactams via an Aza-Heck Reaction
作者:Scott A. Shuler、Guoyin Yin、Sarah B. Krause、Caroline M. Vesper、Donald A. Watson
DOI:10.1021/jacs.6b08932
日期:2016.10.26
The preparation of unsaturated secondary lactams via the palladium-catalyzed cyclization of O-phenyl hydroxamates onto a pendent alkene is reported. This method provides rapid access to a broad range of lactams that are widely useful building blocks in alkaloid synthesis. Mechanistic studies support an aza-Heck-type pathway.