Lycopene-5,6-diol stereoisomers (1a,b) and (2a,b) and γ-carotene-5′,6′-diol stereoisomers (3a,b) and (4a,b) were synthesized by a stepwise C15 + C10 + C15 double Wittig reaction strategy. The key compounds erythro(anti)-C15-dihydroxy aldehydes 17a,b and their threo(syn)-stereoisomers 23a,b were prepared via Sharpless asymmetric epoxidation of geraniol and nerol followed by acidic hydrolysis of the
通过逐步C 15合成番茄红素5,6-二醇立体异构体(1a,b)和(2a,b)和γ-胡萝卜素5',6'-二醇立体异构体(3a,b)和(4a,b) + C 10 + C 15双重维蒂希反应策略。关键化合物赤型(抗)-C 15-二羟基醛17a,b及其苏式(顺式)-立体异构体23a,b是通过香叶醇和神经醇的Sharpless不对称环氧化,然后以立体有择的方式对环氧化物进行酸性水解而制备的。对映体富集反-异构体,通过2,3- epoxygeranyl 3,5- dinitrobenzoates重结晶的方式获得图9A,B,而顺式-异构体是经由dihydroxyneryl 3,5- dinitrobenzoates的重结晶如对映体纯的形式获得的21A,B。为了确定天然产物的绝对立体化学,使用带有手性固定相的色谱柱建立了每种对映体1a,b - 4a,b的HPLC分离方法。
Molybdenum-Catalyzed Hydroxyl-Directed <i>Anti</i>-Dihydroxylation of Allylic and Homoallylic Alcohols
作者:Pei Fan、Shixia Su、Chuan Wang
DOI:10.1021/acscatal.8b01449
日期:2018.8.3
A catalytic hydroxyl-directed anti-dihydroxylation of allylic and homoallylic alcohols has been developed. This operationally simple method was successfully applied to the direct anti-monodihydroxylation of allylic alcohols containing at least one distal olefinic unit. Under the catalysis of commercially available MoO2(acac)2, an array of hydroxylated dienes were successfully converted into various
作者:Timothy J. Donohoe、Peter R. Moore、Michael J. Waring、Nicholas J. Newcombe
DOI:10.1016/s0040-4039(97)01061-7
日期:1997.7
The preparation and dihydroxylation of a series of polyenes and cyclicallylicalcohols using the TMEDA/osmium tetroxide mixture is reported. Remarkably, these reagents lead to high levels of regiochemical and stereochemical control as the oxidant hydrogen-bonds to the allylicalcohol group. A mechanistic hypothesis is presented which invokes the formation of a reactive, bidentate complex between osmium
Hydroquinone and terpene glucosides from Leontopodium leontopodioides and their lipase inhibitory activity
作者:Ping Gou、Yangyang Xiao、Ling Lv、Haihui Xie
DOI:10.1016/j.fitote.2018.08.010
日期:2018.10
Three newglucosides of hydroquinone, monoterpene, and megastigmane, benzyl 2,5-dihydroxybenzoate 5-O-β-d-glucopyranoside (isotrichocarpin, 1), (2S,3R)-3,7-dimethyl-6-octene-1,2,3-triol 2-O-β-d-glucopyranoside (leontopodioside D, 4), and (6R,7R,8R,9S)-6,9-epoxy-7,8-dihydroxymegastigman-4-en-3-one 8-O-β-d-glucopyranoside (leontopodioside E, 7) were isolated from the whole herbs of Leontopodium leontopodioides
A novel synthesis of the aggregation pheromone of the Colorado potato beetle, Leptinotarsa decemlineata, has been developed based on a Sharpless asymmetric epoxidation in combination with a chemoselective alcohol oxidation using catalytic [(neocuproine)PdOAc]2OTf2. Employing this approach, the pheromone was synthesized in 3 steps, 80% yield and 86% ee from geraniol.