[reaction: see text] Stereospecific cyclopropanation of alkenylboronic esters of pinacol followed by in situ treatment with excess KHF(2) afforded the corresponding potassium cyclopropyl trifluoroborates in high yields, which then underwent Suzuki-Miyaura cross-coupling reactions with aryl bromides to give cyclopropyl-substituted arenes in good yields with retention of configuration. This promises to be a useful method for the synthesis of enantiomerically pure cyclopropanes.
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http://dx.doi.org/10.1021/ol036184e | DOI Listing |
Org Lett
September 2019
School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata-700032, India.
This work discloses transamidation of primary and tertiary amides with a range of aryl, heteroaryl, and aliphatic amines using potassium -butoxide. The reaction proceeds at room temperature under transition-metal-free conditions providing secondary amides in high yields. Moreover, reaction of cyclopropyl amine with tertiary amides proceeds with ring-opening to provide a rapid access to enamides.
View Article and Find Full Text PDFBeilstein J Org Chem
May 2019
Département de chimie, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal, Québec, H3C 3P8, Canada.
The copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid is reported. The procedure operates under simple conditions to afford the corresponding aryl cyclopropyl sulfides in moderate to excellent yields. The reaction tolerates substitution in , and -substitution as well as electron-donating and electron-withdrawing groups.
View Article and Find Full Text PDFJ Org Chem
April 2018
Department of Chemistry , The Scripps Research Institute, 10550 North Torrey Pines Road , La Jolla , California 92037 , United States.
Small molecules containing cyclopropane-heteroatom linkages are commonly needed in medicinal chemistry campaigns yet are problematic to prepare using existing methods. To address this issue, a scalable Chan-Lam cyclopropylation reaction using potassium cyclopropyl trifluoroborate has been developed. With phenol nucleophiles, the reaction effects O-cyclopropylation, whereas with 2-pyridones, 2-hydroxybenzimidazoles, and 2-aminopyridines the reaction brings about N-cyclopropylation.
View Article and Find Full Text PDFBioorg Med Chem
August 2017
Research Division, Takeda Pharmaceutical Co., Ltd., 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan.
Somatostatin (SST) is a peptide hormone comprising 14 or 28 amino acids that inhibits endocrine and exocrine secretion via five distinct G-protein-coupled receptors (SSTR1-5). SSTR5 has an important role in inhibiting the secretion of pancreatic and gastrointestinal hormones (e.g.
View Article and Find Full Text PDFEur Rev Med Pharmacol Sci
November 2016
Department of Pharmacology, King Saud University, Riyadh, Saudi Arabia.
Objective: Thrombin is implicated in the genesis of arrhythmias and activation of thrombin receptors exacerbated ventricular arrhythmias following coronary artery ligation. The present study was designed to investigate the possible protective effect of the protease-activated receptor-1 antagonist, SCH79797 against ischemia and reperfusion arrhythmias in the rat heart.
Materials And Methods: Healthy male Wistar rats (250-350 g) were anesthetized with urethane.
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