Oxime-Palladacycle-Catalyzed Suzuki-Miyaura Arylation and Alkenylation of Aryl Imidazolesulfonates under Aqueous and Phosphane-Free Conditions
作者:José Francisco Cívicos、Diego A. Alonso、Carmen Nájera
DOI:10.1002/ejoc.201200368
日期:2012.7
Aryl and hetaroaryl imidazole-1-sulfonates are efficiently arylated and alkenylated with aryl- and alkenylboronic acids and potassium trifluoroborates by using 0.5 mol-% palladacycles 1 or Pd(OAc)2 at 110 °C under aqueous and phosphane-free conditions. Reactions can be performed by using conventional or microwave heating, leading to biaryls, stilbenes, and alkenylarenes in good to high yields, and
heteroaromatic cores are ample and widespread in nature, with many compounds exhibiting promising therapeutic properties. (+)-Armillariol C (1a) is a furan-based natural product isolated from Armillaria species. Herein, we report the first enantioselective synthesis of (+)-armillariol C (1a, 79% overall yield), its enantiomer (1b), and four other analogues, on a gram-scale, using microwave-mediated, Suzuki–Miyaura
The formal synthesis of (+)-15-deoxy-Δ12,14-prostaglandin J2 by utilizing SmI2-promoted intramolecular coupling of bromoalkynes and α,β-unsaturated esters
an SmI2-promoted radicalcyclization as a key reaction. It was conceived that 3 would be assembled from bromolactone 4 utilizing the radicalcyclization, however, 3 could not be obtained under the reaction conditions. On the other hand, the similar coupling reaction of bromoalkyne (R,E)-7a, the desired product syn-8 was given, via 3 for separation of diastereomers. The intermediate syn-8 was then transformed
The formal synthesis of (+)-15-deoxy-Δ12,14-prostaglandin J2: Controlling exo-olefin geometry via SmI2-mediated cyclization
作者:Kazunori Takahashi、Yuichi Arai、Toshio Honda
DOI:10.1016/j.tetlet.2017.09.002
日期:2017.10
A synthetic approach of (+)-15d-PGJ2 has been developed. The present method features a stereoselective construction of the olefin unit using SmI2-mediated radicalcyclization. The resulting cyclic compound was further utilized by efficient introduction of α and ω chains of prostaglandins to achieve enantioselective formal synthesis of (+)-15d-PGJ2.
Microwave enhanced cross-coupling reactions involving alkenyl- and alkynyltrifluoroborates
作者:George W. Kabalka、Abhijit Naravane、Li Li Zhao
DOI:10.1016/j.tetlet.2007.08.002
日期:2007.10
Cross-coupling reactions of potassium alkenyltrifluoroborates and alkynyltrifluoroborates with aryl triflates in the presence of a palladium catalyst occur rapidly utilizing microwave irradiation. The coupled products are generated in good to excellent yields. (c) 2007 Elsevier Ltd. All rights reserved.