Regioselective Synthesis of β‐Aryl‐ and β‐Amino‐Substituted Aliphatic Esters by Rhodium‐Catalyzed Tandem Double‐Bond Migration/Conjugate Addition

Abstract

Rhodium-phosphite catalysts were found to effectively mediate double-bond migrations within unsaturated esters. Once the double-bond is in conjugation with the carboxylate group, they also catalyze the Michael addition of carbon and nitrogen nucleophiles. In the presence of these catalysts, unsaturated carboxylates enter a dynamic equilibrium of positional and geometrical double-bond isomers. The conjugated species are continuously removed through 1,4-additions with formation of β-amino esters or β-arylated products, depending on the nucleophile employed. The applicability of both protocols to a range of substrates, such as fatty esters of different chain lengths and double-bond positions, and several nucleophiles including arylborates and primary and secondary amines, is demonstrated.

Alkene Isomerisation Catalysed by a Ruthenium PNN Pincer Complex

“…Examples include the Evonik/Oxeno isomerising hydroformylation of a mixture of butenes to n-pentanal, [4] and the Dupont process for the production of adiponitrile through isomerising hydrocyanation of 3-pentenenitrile. [5] High yields and selectivities have been obtained for catalysis involving alkene isomerisation in tandem with hydroformylation/reduction to alcohols, [6] methoxycarbonylation, [7] metathesis, [8] conjugate addition, [9] hydroboration, [10] cyclisation [11] and trialkylsilylation. [12] Other examples are the isomerisation of allyl benzenes such as estragol or safrole, which are of great interest for the fragrance industry.…”

Neue Trends in der homogenen Übergangsmetallkatalyse

“…Werden Metathese und Isomerisierung kombiniert, wie von Grubbs [228] und Gooßen [229] gezeigt, kann diese Tandemreaktion dazu genutzt werden, aus langkettigen Substraten, wie z. Eine Isomerisierung der Doppelbindung bei Fettsäuren in Richtung der Carboxylatgruppe macht Lactonisierungen [240] oder Michael-Reaktionen [241] möglich. Aus Fetten können auf diese Weise -lineare C 9 -bis C 26 -Alkene -lineare ungesättigte C 8 -bis C 28 -Methylester und -lineare ungesättigte C 11 -bis C 26 [236], Palladium-katalysiert eine Hydroesterifizierung [237 -239] und Rhodium-katalysiert eine Hydroformylierung zu den a,w-funktionalisierten Produkten durchgeführt werden.…”

“…[236], Palladium-katalysiert eine Hydroesterifizierung[237 -239] und Rhodium-katalysiert eine Hydroformylierung zu den a,w-funktionalisierten Produkten durchgeführt werden. Eine Isomerisierung der Doppelbindung bei Fettsäuren in Richtung der Carboxylatgruppe macht Lactonisierungen[240] oder Michael-Reaktionen[241] möglich.Die Hydroformylierung ist eine schnelle und atomökonomische Methode zur selektiven Synthese von Aldehyden. Sie ist, wie bereits im Abschn.…”

Metathesis of 9-octadecenoic acid methyl ester: diversity and mechanism of product formation at various Grubbs’ catalyst concentrations

“…Depletion of fossil resources and increasing interest in renewable feed stock transformations is constantly growing day by day [1][2][3][4][5][6]. Natural oils and fats are potential sources of unsaturated fatty acids where a number of chemical modifications across the double bonds [7,8] result in a variety of organic intermediates.…”