已经描述了 β,γ-取代的烯丙基硼酸酯对醛的催化不对称加成。在 5 mol% 手性磷酸的促进下,该反应具有广泛的适用性、可扩展性和高效性,允许以高度对映和非对映选择性的方式形成带有相邻叔或季立体中心的 3,4-反/同-高烯丙醇(≤99% ee 和 dr >20:1)。涉及手性磷酸的刚性椅子状过渡态有助于高度控制的反应。
An increase of α-regioselectivity was observed in the reaction of allylic barium reagents with aldehydes employing crown ether as an additive. For example, an α/γ regioselectivity was improved to 98/2 from 92/8, when an equimolar amount of 18-crown-6 was added to geranylbarium reagent in THF at -78 °C prior to the reaction with benzaldehyde.
Barbier-Type Allylation of Aldehydes and Ketones with Metallic Lead in Aqueous Media
作者:Jing-Yao Zhou、Yu Jia、Guang-Fu Sun、Shi-Hui Wu
DOI:10.1080/00397919708006791
日期:1997.6
Abstract Homoallylic alcohols can be obtainedfromallylation of aldehydes and ketones with allyl bromide promoted by metallic lead. These reactions can be carried out smoothly in aqueous media.
In Situ Formation of Allyl Ketones via Hiyama−Nozaki Reactions Followed by a Chromium-Mediated Oppenauer Oxidation
作者:Henri S. Schrekker、Martin W. G. de Bolster、Romano V. A. Orru、Ludger A. Wessjohann
DOI:10.1021/jo001750u
日期:2002.4.1
dependent on the substitution pattern of the reaction partners and the reaction conditions. An appropriate choice of these can lead to preferential formation of ketones instead of the alcohols. In addition to its synthetic usefulness, the oxidation-reduction equilibrium is of the utmost importance for the design of enantioselective Hiyama-Nozaki reactions because it is also a potential racemization pathway
Forging C–C Bonds with Hindered Nucleophiles and Carbonyl Electrophiles: Reactivity and Selectivity of Allylic Tin Reagents/<i>n</i>-BuLi
作者:Morgan Cormier、Maha Ahmad、Jacques Maddaluno、Michaël De Paolis
DOI:10.1021/acs.organomet.7b00765
日期:2017.12.26
tertiary alcohols that are vicinal to quaternary carbons. With α,α′-dimethoxy-γ-pyrone, on the other hand, the grafting of a dienyl side chain was effected to prepare dienyl α′-methoxy-γ-pyrone in a stereo- and regioselective and convergent manner. Furthermore, the advantages of this route were highlighted for the preparation of organolithium species at low temperature with the formation of a minimum
Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
作者:Jinping Yuan、Pankaj Jain、Jon C. Antilla
DOI:10.1021/acs.joc.0c01646
日期:2020.10.16
catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiralphosphoricacids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiomeric excess (ee), diastereomeric ratio (dr) >20:1). These boronate substrates provided superior enantioselectivities, allowing for the reactions to proceed with low catalyst loading