Aminium salts catalyzed rearrangement of α-pinene and β-ionone oxides
摘要:
beta-ionone and alpha-pinene oxides 1, 3 isomerize rapidly and selectively to 1-(1,2,2-trimethylcyclopent-1-yl)-pent-2-en-1.4-dione 2 and the industrially important 2,2,3-trimethyl-3-cyclopentene acetaldehyde 4. under the influence of catalytic amounts of aminium salts A,B. In order to find insights into the mechanism of our procedure, protic and Lewis acids-catalyzed rearrangements have also been reconsidered.
Sulfonic peracids — III. Heteroatom oxidation and chemoselectivity
作者:R. Kluge、M. Schulz、S. Liebsch
DOI:10.1016/0040-4020(96)00202-5
日期:1996.4
investigated thep-toluenesulfonic peracid (2) generated in situ in the oxidation of different types of compounds containing nitrogen and/or sulfur. The sulfonic peracid2 shows a remarkable chemoselectivity characterized by a preferred oxidation of sulfides to the sulfones in the presence of amines or olefins and a strong dependence on the nature of the amine in the competitive oxidation of olefins and amines.
A Cheap, Catalytic, Scalable, and Environmentally Benign Method for Alkene Epoxidations
作者:Benjamin S. Lane、Kevin Burgess
DOI:10.1021/ja004000a
日期:2001.3.1
aliphatic alkenes can be selectively epoxidized in the presence of terminal alkenes. This experiment also implies that the allylic hydroxyl does not activate the terminal alkene via a directing effect. Entries 9-12 illustrate that epoxidations of arylsubstituted alkenes proceed smoothly; qualitatively, the rates of these reactions were observed to be appreciably faster than for aliphatic alkenes. The only
烯烃环氧化的良性方法 Benjamin S. Lane 和 Kevin Burgess* 德克萨斯 A & M 大学化学系 PO Box 30012, College STAtion, Texas 77842-3012 收到 2000 年 11 月 17 日 本文报告了一种简单的方法,其中锰 (2+)盐,例如 MnSO4,使用 30% 的过氧化氢水溶液作为末端氧化剂催化烯烃的环氧化。通过将底物和催化剂溶解在 DMF 或叔丁醇中,然后缓慢加入 30% 过氧化氢和 0.2 M 碳酸氢钠缓冲液的混合物来进行反应。这种方法在成本、简单性和环境因素方面有几个理想的属性。该项目来自在筛选新的、手性的、1,4、7-三氮杂环壬烷 (TACN) 配合物作为潜在的不对称环氧化催化剂。在一个简单的平板装置 1 中的高通量筛选表明,没有任何有机配体的简单锰 (2+) 盐介导了环氧化,但仅在碳酸氢盐缓冲液中。在基于
Diastereoselective epoxidation of olefins by organo sulfonic peracids, II
作者:R. Kluge、M. Schulz、S. Liebsch
DOI:10.1016/0040-4020(95)01128-5
日期:1996.2
have investigated the behaviour of sulfonic peracids 2in situ generated towards olefins 7a,7b,9,11,14,16,18, allylic and homoallylic alcohols 20,22,24,26,28,30,33 and α,β-unsaturated ketones 35,37,39. Generally, the epoxidation proceeds in a peracid-like manner with greater diastereoselectivity than those by common oxidants. In particular, the epoxidation of Δ4 3-ketosteroids 39a-i led to 4α,5α-epoxides
The chemistry of terpenes. Part XIV. Syntheses of (±)- and (+)-fenchone, and (+)-cis-2,2,5-trimethyl-3-vinylcyclopentanone, a photoisomer of (–)-trans-caran-4-one
作者:P. H. Boyle、W. Cocker、D. H. Grayson、P. V. R. Shannon
DOI:10.1039/j39710002136
日期:——
Treatment of (+)-α-2,3-epoxypinane or (–)-trans-pinocarveol with hydrogen bromide gives a mixture in which (–)-2-endo-bromo-6-exo-hydroxy-1,3,3-trimethylbicyclo[2,2,1]heptane is the major product. With silver acetate this affords (–)-2,2,4-trimethylcyclopent-3-enylacetaldehyde, which gives (–)-4-(2-hydroxyethyl)-1,3,3-trimethylcyclopentene on reduction. The alcohol reacts with peracetic acid giving
Substrate-Induced Diastereoselectivity in the Dimethyldioxirane Epoxidation of Simple Alkenes and Dienes
作者:Amalia Asouti、Lazaros P. Hadjiarapoglou
DOI:10.1055/s-2001-18751
日期:——
Various alkenes and dienes, such as (R)- or (S)-limonene 2, 2-carene 6, 3-carene 8, (R)-α-pinene 10, (S)-α-pinene 12, and endo-dicyclopentadiene 14 were transformed into the corresponding mono- and bis-epoxides by epoxidation with dimethyldioxirane (as an acetone solution). The selectivity observed in these epoxidations is explained by the assumption of hydrogen bonding between bridge protons and the dioxirane.