The t-BuOK promoted stereoselective isomerization of allylarylethers has been developed. The reactions proceeded well in methyl tert-butyl ether (MTBE), providing the corresponding products in good to excellent yields (83–96%). Most of the substrates were isomerized predominantly to the Z isomers with excellent stereoselectivities. Gram-scale synthesis was also achieved on a 10 mmol scale. Moreover
A new route to the regioisomeric 2-alkylnaphtho[2,1-b]- and 2-alkylnaphtho[1,2-b]furans via acid-catalyzed cyclization of the corresponding 2-naphthyloxyalkanals under mild conditions over Amberlyst 15 resin has been described. The 2-naphthyloxyalkanals were obtained by palladium-catalyzed reduction of 2-naphthyloxyalkanoyl chlorides.
Photoinduced Vitamin B<sub>12</sub>-Catalysis for Deprotection of (Allyloxy)arenes
作者:Maciej Giedyk、Joanna Turkowska、Sandra Lepak、Marcin Marculewicz、Keith ó Proinsias、Dorota Gryko
DOI:10.1021/acs.orglett.7b01012
日期:2017.5.19
VitaminB12 is a natural cobalt complex that, while reduced to the “supernucleophilic” Co(I) form, can easily react with electrophiles via an SN2 mechanism. It is also shown to react via an SN2′ mechanism with allylic compounds allowing for photochemical deprotection of (allyloxy)arenes. A sustainable alternative to commonly used noble metal-catalyzed deprotection reactions is presented.
维生素B 12是一种天然钴配合物,虽然还原为“超亲核” Co(I)形式,但可以通过S N 2机理与亲电子反应。它也表明通过S反应Ñ与烯丙基化合物允许的(烯丙氧基)芳烃光化学脱保护2'机制。提出了一种常用的贵金属催化的脱保护反应的可持续替代方法。
Lewis acid promoted double bond migration in O-allyl to Z-products by Ru-H complexes
and convenient ruthenium(II) complex for the catalyticisomerization of O-allylethers, leading to thermodynamic-unfavored Z-product under mild conditions. The model substrate of allyl phenyl ether can be simply scaled up to 20 mmol to produce Z-product with TON of 2453 and TOF of 13,430 h−1 at 40–60 °C. The system of Ru(II)/Lewis Acidcatalysts was suitable for various substituted O-allylethers and other
在催化双键迁移反应中,通常以E-构型烯烃为主要产物,因为E-构型在热力学上是有利的。然而,由于结构-活性关系,有时在药物化学中需要Z-构型产物。在本文中,我们证明了一种新的策略,即路易斯酸促进了广泛使用且方便的钌(II)络合物用于O-烯丙基醚的催化异构化,导致在温和条件下产生热力学不利的Z产物。烯丙基苯基醚的模型底物可以简单地按比例放大至20 mmol以生产TON为2453,TOF为13,430 h -1的Z产物在40–60°C下。Ru(II)/路易斯酸催化剂体系适用于各种取代的O-烯丙基醚和其他类型的底物。通过包括动力学研究,配体抑制作用和分子光谱在内的机理研究,通过添加路易斯酸使PPh 3配体解离,以及由嵌合助剂形成五元Ru络合物均被认为是提高反应性和稳定性的必要步骤。通过金属氢化物加成消除机理控制催化双键迁移反应的立体选择性。这一新策略可能为生产用于药物化学的杂环化合物中热力学不利的产品提供新的机会。
Pd-Catalyzed Tandem Isomerization/Cyclization for the Synthesis of Aromatic Oxazaheterocycles and Pyrido[3,4-<i>b</i>]indoles
作者:Linglong Ding、Yan-Ning Niu、Xiao-Feng Xia
DOI:10.1021/acs.joc.1c00770
日期:2021.8.6
An effient tandem process consisting of palladium-catalyzed double-bond isomerization of long-chain olefins and subsequent intramolecular cyclization promoted by B2(OH)2 for the synthesis of aromatic oxazaheterocycles is disclosed. This strategy can also provide rapid access to pyrido[3,4-b]indoles, trans-2-olefins, and eneamides bearing various functional groups with high regio- and stereoselectivity
公开了一种由钯催化的长链烯烃双键异构化和随后由 B 2 (OH) 2促进的分子内环化合成芳族氧杂杂环的有效串联方法。该策略还可以快速获得具有高区域和立体选择性的各种官能团的吡啶并[3,4- b ]吲哚、反式-2-烯烃和烯酰胺。