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27 Nov 23:13

An efficient and highly diastereoselective synthesis of carbocyclic spiropyrazolones via one-pot sequential dual organo-silver catalyzed Michael-hydroalkylation reactions

Publication date: 3 January 2019

Source: Tetrahedron Letters, Volume 60, Issue 1

Author(s): Khyati Shukla, Sadhna Shah, Nirmal K. Rana, Vinod K. Singh

Abstract

An economical approach for the diastereoselective synthesis of highly functionalized carbocyclic spiropyrazolone derivatives having one quaternary and two tertiary stereocenters along with one exocyclic double bond exploiting dual organo-silver sequential catalysis has been developed. The unified method to both cyclohexyl and cyclopentyl spirocompounds involves the reaction of γ- and β-nitroalkynes with alkylidene pyrazolones catalyzed by Hünig’s base followed by carbophilic activation of the triple bond with a Ag(I) salt leading to cyclization via hydroalkylation.

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Graphical abstract for this article

03 Aug 10:27

[ASAP] Catalyst Activation, Chemoselectivity, and Reaction Rate Controlled by the Counterion in the Cu(I)-Catalyzed Cycloaddition between Azide and Terminal or 1-Iodoalkynes

by Ryan Chung, Anh Vo, Valery V. Fokin, Jason E. Hein

TOC Graphic

ACS Catalysis
DOI: 10.1021/acscatal.8b01342
19 Mar 19:26

Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl) methane

by Betterley, Nolan M.

Synthesis
DOI: 10.1055/s-0036-1591545



Difluoro(phenylsulfanyl)methane (PhSCF2H) was found to undergo a reaction with aromatic compounds mediated by SnCl4, through a thionium intermediate characterized by NMR and TD-DFT analyses, leading to the formation of a mixture of S,S′-diphenyl dithioacetal and aromatic aldehyde which, after oxidative hydrolysis, provides the aromatic aldehyde in good to excellent yields. The salient feature of the present work is the reaction of activated aromatic compounds containing a deactivating ester functional group, leading to the formylated products in good yields.
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© Georg Thieme Verlag Stuttgart · New York

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

18 Mar 07:29

Frontispiece: Enantioselective Brønsted Acid Catalysis as a Tool for the Synthesis of Natural Products and Pharmaceuticals

by Jérémy Merad, Claudia Lalli, Guillaume Bernadat, Julien Maury, Géraldine Masson
Thumbnail image of graphical abstract

Chiral Brønsted acids are capable of promoting plenty of enantioselective transformations. From simple substrates, chiral protons build complex enantioenriched scaffolds that are subsequently involved in the total synthesis of bioactive moieties. This review aims to describe the value of such asymmetric catalysis to the synthesis of natural products and pharmaceuticals. The target structures, and the potential disconnections are particularly emphasized. For more information see the Minireview by G. Masson and co-workers on page 3925 ff.

01 Mar 09:43

Catalytic Enantioselective Transformations Involving C–H Bond Cleavage by Transition-Metal Complexes

by Christopher G. Newton, Shou-Guo Wang, Caio C. Oliveira and Nicolai Cramer
Maximevitale

Nice !

TOC Graphic

Chemical Reviews
DOI: 10.1021/acs.chemrev.6b00692