Practical Application of the Aqueous ‘Sulfonyl-Azide-Free’ (SAFE) Diazo Transfer Protocol to Less α-C–H Acidic Ketones and Esters
作者:Dmitry Dar’in、Grigory Kantin、Mikhail Krasavin
DOI:10.1055/s-0039-1690613
日期:2019.11
Abstract The earlier described ‘sulfonyl-azide-free’ (‘SAFE’) protocol for diazo transfer to CH-acidic 1,3-dicarbonyl compounds (and their similarly activated congeners) has been extended to the less reactive monocarbonyl substrates, which previously required a separate activation step. Formylation in situ, followed by the addition of an optimized amount of the ‘SAFE cocktail’ (obtained by mixing sodium
Ternary Catalysis Enabled Three-Component Asymmetric Allylic Alkylation as a Concise Track to Chiral α,α-Disubstituted Ketones
作者:Zhenghui Kang、Wenju Chang、Xue Tian、Xiang Fu、Wenxuan Zhao、Xinfang Xu、Yong Liang、Wenhao Hu
DOI:10.1021/jacs.1c09148
日期:2021.12.15
unknown. Herein, a three-component asymmetric allylation of α-diazo carbonyl compounds with alcohols and allyl carbonates is disclosed by employing a ternary cooperative catalysis of achiral Pd-complex, Rh2(OAc)4, and chiral phosphoric acid CPA. This method represents the first example of three-component asymmetric allylic alkylation through an SN1-type trapping process, which involves a convergent assembly
涉及通过 Aldol、Mannich 和 Michael 加成拦截鎓叶立德与相应的台式受体的多组分反应已证明在合成化学中具有广泛的应用。然而,由于这些原位生成的中间体的高反应性和瞬时存活,取代型拦截过程,尤其是不对称催化形式,至今仍是未知的。在此,通过采用非手性 Pd 络合物 Rh 2 (OAc) 4的三元协同催化,公开了 α-重氮羰基化合物与醇和碳酸烯丙酯的三组分不对称烯丙基化反应。, 和手性磷酸 CPA。该方法代表了通过 S N 1 型捕获过程的三组分不对称烯丙基烷基化的第一个示例,该过程涉及两种活性中间体 Pd-烯丙基物质和源自鎓叶立德的烯醇的聚合组装,提供了快速获得手性 α,α-二取代酮,产率好至高,对映选择性高至优异。结合实验和计算研究揭示了这种新型三组分反应的机制,包括 Xantphos 配体的关键作用和对映选择性的起源。
Generation, observation, and reactivity of furyl- and thienylketenes and bisketenes
作者:Nanyan Fu、Annette D Allen、Winnie Chan、Shinjiro Kobayashi、Thomas T Tidwell、Daryoush Tahmassebi、Angelica Aguilar、Eduardo Peña Cabrera、Jazmin Godoy
DOI:10.1139/v08-021
日期:2008.4.1
2- and 3-Furylketenes (18 and 20), 2- and 3-thienylketenes (19 and 21), and bis(2,5-ketenyl)thiophene (24) have been generated as observable reactive intermediates by photochemical Wolff rearrangements. Stabilization energies of the monoketenes 18–21 have been determined by DFT computations of isodesmic energy changes, and these ketenes are predicted to be modestly destabilized relative to phenylketene
relationship studies revealed that carbonylmethyl groups at both N-1 and N-5 positions and hydrophilic groups, such as the carboxyl group on the benzene ring attached to the ureido group at the C-3 position, brought about potent affinity and subtype selectivity for CCK-B/gastrin receptors. Several compounds showed excellent in vivo inhibition of gastric acid secretion induced by pentagastrin in anesthetized
Abstract [3+2]-Cycloaddition of arenediazonium salts with diazo compounds (earlier exemplified only for trimethylsilyldiazomethane and 2,2,2-trifluorodiazoethane) has been developed to include a wide range of readily available α-diazocarbonyl compounds. The resulting 2-aryl-5-acyl-2H-tetrazoles are of high value in medicinal chemistry. [3+2]-Cycloaddition of arenediazonium salts with diazo compounds