Radical α-C−H Hydroxyalkylation of Ethers and Acetal
摘要:
Ethers and an acetal were found to undergo direct intermolecular addition to aldehydes under the Et3B/air conditions. This study presents a very unique and simple means for the radical alpha-C-H hydroxyalkylation of oxygen-containing compounds.
Role of the methoxy group in product formation via TiCl4 promoted 4-phenyldioxolane isomerizationsons
作者:Ivan Robert Green、Natasha October
DOI:10.3998/ark.5550190.0011.206
日期:——
The product distribution obtained from the TiCl4 initiated intramolecular isomerizations of 4methoxyphenyland trimethoxyphenyldioxolanes at -78 C, -30 C and 0 C provided insights into the important regiochemical role played by these groups in such Mukaiyamatype rearrangements through their resonance effects on the aryl ring of the dioxolanes.
hoxypropane (1), only deprotonation of the radicalcation is observed. In contrast, removing the ring methoxy group leads to exclusive C−C bond cleavage in the radicalcation. Replacing the side-chain β-OMe by β-OH, the radicalcation undergoes both C−C and C−H bond cleavage, with both pathways being base catalyzed. C−C bond breaking in the radicalcation is also enhanced by an α-OH group, as shown
Neurotropic Components from Star Anise(Illicium verum HooK. fil.).
作者:Tomonori NAKAMURA、Emi OKUYAMA、Mikio YAMAZAKI
DOI:10.1248/cpb.44.1908
日期:——
Three new neurotropic sesquiterpenoids, veranisatins A, B and C, were isolated from star anise (Illicium verum HOOK. fil., Illiciaceae). Veranisatins showed convulsion and lethal toxicity in mice at a dose of 3 mg/kg (p.o.), and at lower doses they caused hypothermia. Veranisatin A and the related compound, anisatin, were tested for the other pharmacological activities such as locomotor activity and analgesic effect. Both compounds decreased the locomotion enhanced by methamphetamine at oral doses of 0.1 and 0.03 mg/kg, respectively, and demonstrated the analgesia on acetic acid-induced writhing and tail pressure pain at almost similar doses.
从八角茴香(Illicium verum HOOK. fil.,Illiciaceae)中分离出三种新的神经活性倍半萜化合物,veranisatins A、B和C。veranisatins在小鼠体内以3 mg/kg(口服)的剂量表现出癫痫发作和致死毒性,而在较低剂量下则引起体温过低。对veranisatin A及其相关化合物anisatin进行了其他药理活性测试,如运动活性和镇痛效果。这两种化合物分别在0.1和0.03 mg/kg的口服剂量下减少甲基苯丙胺增强的运动活动,并在几乎相同的剂量下显示出对乙酸诱导的扭体和尾部压迫疼痛的镇痛作用。
Spontaneous Hydrolysis Reactions of <i>cis</i>- and <i>trans</i>-β-Methyl-4-methoxystyrene Oxides (Anethole Oxides): Buildup of <i>trans</i>-Anethole Oxide as an Intermediate in the Spontaneous Reaction of <i>cis</i>-Anethole Oxide
作者:Ram S. Mohan、Kostas Gavardinas、Sampson Kyere、Dale L. Whalen
DOI:10.1021/jo991521b
日期:2000.3.1
primary products of the spontaneous reaction of 2 are (4-methoxyphenyl)acetone (73%) and threo-1-(4-methoxyphenyl)-1,2-propanediol (ca. 3%). The rates and products of the spontaneous reaction of 2 and its beta-deuterium-labeled derivative were determined, and the lack of significant kinetic and partitioning deuterium isotopeeffects indicates that the isomerization of 2 to ketone and to trans-anethole
Clean-Up of a Pesticide--Lanolin Mixture by Gel Permeation Chromatography
作者:M. Lopez-Mesas、M. Crespi、J. Brach、J. P. Mullender
DOI:10.1093/chromsci/38.12.551
日期:2000.12.1
In this study, the efficiency of a clean-up method by gelpermeationchromatography (GPC) for the separation of pesticides from lanolin is analyzed. The pesticides analyzed belong to two different families, organophosphorous and synthetic pyrethroids. Lanolin, a standard mixture of the pesticides, and a lanolin-pesticides mixture are injected in a GPC column. The recoveries and elution times from the