The generation of pyridynes from diyne nitriles is reported. These cyano-containing precursors are analogs of the triyne substrates typically used for the hexadehydro-Diels-Alder (HDDA) cycloisomerization reactions that produce ring-fused benzynes. Hence, the new processes described represent aza-HDDA reactions. Depending on the location of the nitrile, either 3,4-pyridynes (from 1,3-diynes containing
Chemoselective Electrophilic Oxidation of Heteroatoms by Hydroperoxy Sultams
作者:Feyissa Gadissa Gelalcha、Bärbel Schulze
DOI:10.1021/jo0202841
日期:2002.11.1
of the latter with acidified H2O2. Kinetic studies of the reaction of 1c with 1,4-thioxane 12f suggest that the reaction follows the second-order kinetics, first order in substrate and first order in oxidant with the second-order rate constant several orders of magnitude larger than that of the corresponding reaction with hydrogen peroxide and tert-butyl hydroperoxide without the need for any acid
描述了新型氢过氧阿马酸1b-d的合成及其作为非水介质中广泛的氮,硫和磷杂原子的可再生化学选择性亲电子氧化剂的潜力。1b,c与仲胺10f,g的反应产生羟基磺酰胺2b,c和硝酮11f或自由基11g,这取决于底物和化学计量,而叔胺10a-d给出氧化胺11a-d。化合物1c,d将各种硫醚12a-g平滑地氧化为亚砜13a-g,其通过色谱法以接近定量的产率分离。通过用酸化的H 2 O 2处理2c,从1c再生出1c。1c与1,4-噻吨12f反应的动力学研究表明,该反应遵循二级动力学,底物上的第一级和氧化剂中的第一级,其第二级速率常数比与过氧化氢和叔丁基氢过氧化物的相应反应的速率大几个数量级,而无需任何酸或重金属催化剂。膦14a,b也被1c容易地以定量收率氧化成各自的膦氧化物15a,b。反应可以在环境温度或更低的温度下进行,并且似乎是通过非自由基机理进行的。反应对空间和电子因素均敏感。b容易获得定量产量。
Synthesis of Substituted Azulenes via Pt(II)-Catalyzed Ring-Expanding Cycloisomerization
Substituted azulenes, valuable structures for electronic devices and pharmaceuticals, have been synthesized by the platinum(II)-catalyzed intramolecular ring-expanding cycloisomerization of 1-en-3-yne with ortho-disubstituted benzene. This novel method provides an alternative route for the efficient synthesis of substituted azulenes. The reaction mechanism of selected catalytic transformations was
NUCLEAR MAGNETIC RESONANCE STUDIES: IX. THE CHEMICAL SHIFT OF THE FORMYL PROTON IN ALIPHATIC ALDEHYDES
作者:R. E. Klinck、J. B. Stothers
DOI:10.1139/v66-008
日期:1966.1.1
The effects of structure on the shielding of formyl protons of aliphatic aldehydes have been examined. The survey included examples of acyclic, alicyclic, and α, β-unsaturated aldehydes. The potential use of these results as an aid for structural elucidations is discussed, and the limitations are noted.
Two-Step Synthesis of 3,4-Dihydropyrrolopyrazinones from Ketones and Piperazin-2-ones
作者:Cosme Sandoval、Ngiap-Kie Lim、Haiming Zhang
DOI:10.1021/acs.orglett.8b00197
日期:2018.2.16
An expedient two-stepsynthesis of 3,4-dihydropyrrolopyrazinones has been achieved via a Vilsmeier–Haack reaction of ketones, followed by an annulation of the corresponding chloroaldehydes with commercially available piperazin-2-ones. A variety of cyclic and acyclic ketones and piperazin-2-ones participated in this two-step chemistry, affording the desired 3,4-dihydropyrrolopyrazinones in up to 78%