The synthesis of carboxylic acid derivatives from unsaturated hydrocarbons is an important process for the preparation of polymers, pharmaceuticals, cosmetics and agrochemicals. Despite its industrial relevance, the traditional Reppe-type carbonylation reaction using pressurized CO is of limited applicability to laboratory-scale synthesis because of: (1) the safety hazards associated with the use of CO, (2) the need for special equipment to handle pressurized gas, (3) the low reactivity of several relevant nucleophiles and (4) the necessity to employ different, often tailor-made, catalytic systems for each nucleophile. Herein we demonstrate that a shuttle-catalysis approach enables a CO- and HCl-free transfer process between an inexpensive reagent, butyryl chloride, and a wide range of unsaturated substrates to access the corresponding acid chlorides in good yields. This new transformation provides access to a broad range of carbonyl-containing products through the in situ transformation of the reactive acid chloride intermediate. In a broader context, this work demonstrates that isodesmic shuttle-catalysis reactions can unlock elusive catalytic reactions.

A catalytic pinacol-type reductive rearrangement reaction of internal 1,2-diols is reported herein. Several scaffolds not usually amenable to pinacol-type reactions, such as aliphatic secondary-secondary diols, undergo the transformation well without the need for prefunctionalization. The reaction uses a simple boron catalyst and two silanes and proceeds through a concerted, stereoinvertive mechanism that enables the preparation of highly enantiomerically enriched products. Computational studies have been used to rationalize the preference for migration over direct deoxygenation.

We demonstrate that a simple Co(III)-complex can efficiently catalyze the cleavage of unstrained C−C bonds via the βcarbon elimination of secondary and tertiary alcohols bearing a directing group. The cobalt-aryl intermediate generated under the reaction conditions can be trapped by different electrophiles to generate a new carbon−carbon bond. Some essential features of this new Co-based mechanistic manifold were revealed by preliminary mechanistic studies.

In this review, recent progress in total syntheses of ent-kaurane diterpenoids from 2015 to date are presented, and key transformations for strategic bond formation are highlighted.

We report an efficient and broadly applicable palladium-catalyzed iodination of inexpensive and abundant aryl and vinyl carboxylic acids via in situ activation to the acid chloride and formation of a phosphonium salt. The use of 1iodobutane as iodide source in combination with a base and a deoxychlorinating reagent gives access to a wide range of aryl and vinyl iodides under Pd/Xantphos catalysis, including complex drug-like scaffolds. Stoichiometric experiments and kinetic analysis suggest a unique mechanism involving CÀP reductive elimination to form the Xantphos phosphonium chloride, which subsequently initiates an unusual halogen exchange by outer sphere nucleophilic substitution.

A catalytic pinacol‐type reductive rearrangement reaction of internal 1,2‐diols is reported herein. Several scaffolds not usually amenable to pinacol‐type reactions, such as aliphatic secondary–secondary diols, undergo the transformation well without the need for prefunctionalization. The reaction uses a simple boron catalyst and two silanes and proceeds through a concerted, stereoinvertive mechanism that enables the preparation of highly enantiomerically enriched products. Computational studies have been used to rationalize the preference for migration over direct deoxygenation.

Wirb erichten über eine effiziente und breit anwendbare Palladium-katalysierte Iodierung günstiger und leichtverfügbarer Aryl-und Vinylcarbonsäuren durch In-situ-Aktivierung zum Säurechlorid und Bildung eines Phosphoniumsalzes.D ie Verwendung von 1-Iodbutan als Iodidquelle in Kombination mit einer Base und einem Desoxychlorierungsreagenz erçffnet den Zugang zu einer Vielzahl von Aryl-und Vinyliodiden unter Pd/Xantphos-Katalyse,e inschließlich komplexer arzneimittelähnlicher Strukturen. Stçchiometrische Experimente und kinetische Analysen legen einen einzigartigen Mechanismus nahe,w elcher die reduktive C-P-Eliminierung zur Bildung des Xantphos-Phosphoniumchlorids beinhaltet, welches anschließend einen ungewçhnlichen Halogenaustauschdurch nukleophile Substitution initiiert. EinleitungOrganische Halogenide gehçren zu den am weitesten verbreiteten funktionellen Gruppen in der organischen Chemie und reichen in ihrer Anwendung von Naturstoffen, [1] Pharmazeutika [2] und Agrochemikalien [3] bis hin zu funktionellen Materialien [4] und molekularer Erkennung. [5] Darüber hinaus sind Halogenide wichtige Bausteine in der organischen Chemie und dienen als synthetische Ansatzpunkte,z.B.durch Aktivierung der Kohlenstoff-Halogen-Bindung mit Übergangsmetallen, [6] Metall-Halogen-Austausch [7] oder nukleophile Substitution. [8] Zahlreiche Methoden zur Bildung von Ruthenium-, [9] Rhodium-, [10] Nickel-, [11] Kupfer-katalysierten [12] und übergangsmetallfreien [13] C(sp 2 )-Halogen-Bindungen wurden bisher beschrieben. [6] In den letzten Jahrzehnten