Search results for " Synthesis"

Organocatalytic enantioselective functionalization of indoles in the carbocyclic ring with cyclic imines

2019

[EN] An organocatalytic enantioselective functionalization in the carbocyclic ring of indoles with benzoxathiazine 2,2-dioxides is described using a quinine-derived bifunctional organocatalyst. This aza-Friedel-Crafts reaction provides 4-indolyl, 5-indolyl and 7-indolyl sulfamidate derivatives in good yields (up to 99%) and with moderate to high enantioselectivities (up to 86% ee).

A Combination of Visible-Light Organophotoredox Catalysis and Asymmetric Organocatalysis for the Enantioselective Mannich Reaction of Dihydroquinoxal…

2019

[EN] An enantioselective photooxidative Mannich reaction of dihydroquinoxalinones with ketones by the merger of organophotoredox and asymmetric organocatalysis is described. This protocol features very mild reaction conditions using simple and cheap catalysts (Eosin Y and (S)-Proline) for the synthesis of chiral quinoxaline derivatives with good to high yields (up to 94%) and excellent enantioselectivities (up to 99% ee).

A Highly Active System for the Metal-Free Aerobic Photocyanation of Tertiary Amines with Visible Light: Application to the Synthesis of Tetraponerine…

2015

A highly efficient metal-free catalytic system for the aerobic photocyanation of tertiary amines with visible light is reported. The use of air as terminal oxidant offers an improved safety profile compared with pure oxygen, the used compact fluorescent lamp (CFL) light sources are highly economical, and no halogenated solvents are required. This system not only proves to be effective for a wide variety of trialkylamines, pharmaceuticals, and alkaloids but remarkably also allows the lowest catalyst loading (0.00001 mol% or 0.1 ppm) ever reported for an organic dye. Bruylants reactions and C-alkylation/decyanations were performed on the obtained α-aminonitriles to demonstrate the postfunctio…

Cover Feature: Total Synthesis of a Partial Structure from Arabinogalactan and Its Application for Allergy Prevention (Chem. Eur. J. 3/2021)

2020

Stereoselective synthesis of the naturally occurring 2-pyranone dodoneine

2008

The first total synthesis of the naturally occurring dihydropyranone dodoneine is reported. Asymmetric allylation reactions were used for the stereoselective generation of the two stereogenic centers. The pyranone ring was created by ring-closing metathesis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Recent advances in the synthesis of functionalised monofluorinated compounds.

2018

Over the past few years, we have tackled the synthesis of interesting monofluorinated organic molecules, such as: dihydronaphthalene derivatives, β-fluoro sulfones and related carbonyl compounds, fluorohydrins and allylic alcohols. Overall, a wide range of modern synthetic techniques are covered in this feature article including transition-metal, photo- and organocatalysis, nucleophilic and electrophilic fluorinations, chiral auxiliaries and enantioselective catalysis.

Diastereoselective Synthesis of 2-Phenylselenenyl-1,3-anti-Diols and 2-Phenylselenenyl-1,3-anti-Azido-Alcohols via Hydroxy- and Azido-Selenenylation …

2005

A method to synthesize 2-phenylselenenyl-1,3-anti-diols and 2-phenyl- selenenyl-1,3-anti-azidoalcohols via hydroxy- or azido-selenenylation of trans-allylic alcohols is reported. Moreover, the first example of hydroxyl-selenenylation of an allylic azide is presented. Yields ranging from moderate to good and diastereomeric ratios up to 95:5 are achieved.

Solid-phase synthesis of a glycopeptide from the homophilic recognition domain of epithelial cadherin 1 using a O-pentafluorophenyluronium salt

1998

Abstract The β-turn forming glycopeptide 6 from the homophilic recognition domain of mouse epithelial cadherin 1 carrying a T N -antigen side chain was synthesised on solid phase using an allylic anchor and the new coupling reagent N , N - N ′, N ′-bis(tetramethylene)- O -pentafluorophenyluronium hexafluorophosphate 3 .

New approaches to the synthesis of organofluorine nitrogenated derivatives

2004

Fluorinated carboxylic acids are valuable building blocks for several types of organofluorine nitrogenated derivatives. In this review paper, several strategies that use these compounds as starting materials are described. First, fluorinated seven-membered cyclic β-amino esters can be diastereoselectively synthesized from these compounds with a ring-closing metathesis (RCM) reaction as the key step. The use of the RCM reaction in a different approach enables the preparation of fluorinated cyclic α-amino acid derivatives. Fluorinated carboxylic acids also constitute the starting material for the asymmetric synthesis of fluorinated allylic amines. Finally, a solution and solid-phase synthesis…

Novel Approach for Asymmetric Synthesis of Fluorinated β-Amino Sulfones and Allylic Amines

2003

[reaction: see text] Enantiomerically pure gamma-fluoroalkyl beta-amino sulfones are readily synthesized in three steps starting from fluorinated imidoyl chlorides and arylmethyl sulfones. A complementary two-step sequence starting from chiral fluorinated beta-amino sulfoxides has also been developed. To illustrate the application of this procedure, a new method for the synthesis of alpha-fluoroalkyl allylic amines in optically pure form involving a Julia methylenation-desulfonylation reaction is presented.