Search results for "cyanation"

TiO2 Nanoparticles Functionalized with Non-innocent Ligands Allow Oxidative Photocyanation of Amines with Visible/Near-Infrared Photons

2018

Photosynthesis is an efficient mechanism for converting solar light energy into chemical energy. We report on a strategy for the aerobic photocyanation of tertiary amines with visible and near-infrared (NIR) light. Panchromatic sensitization was achieved by functionalizing TiO2 with a 2-methylisoquinolinium chromophore, which captures essential features of the extended π-system of 2,7-diazapyrenium (DAP2+) dications or graphitic carbon nitride. Two phenolic hydroxy groups make this ligand highly redox-active and allow for efficient surface binding and enhanced electron transfer to the TiO2 surface. Non-innocent ligands have energetically accessible levels that allow redox reactions to chang…

Input of P, N-(phosphanyl, amino)-ferrocene hybrid derivatives in late transition metals catalysis

2018

International audience; Unequally functionalized ferrocenes give access to valuable hemilabile reactivity in catalytic reaction. We address the synthesis of hybrid (P, N)-ferrocenyl compounds for which recent catalytic breakthrough applications have been reported, transversely in late transition metals chemistry. Palladium, nickel, rhodium, iridium, and emerging iron and gold catalysis are illustrated from selected examples, which include CC bond formation from cross-coupling and polymerization, allylic substitution, cyanation, hydroformylation, CH arylation and silylation and hydrogenation reactions.

Dehydrogenative Anodic Cyanation Reaction of Phenols in Benzylic Positions

2019

An efficient and practical synthesis of [2-11C]indole via superfast nucleophilic [11C]cyanation and RANEY® Nickel catalyzed reductive cyclization

2015

A rapid method for the synthesis of carbon-11 radiolabeled indole was developed using a sub-nanomolar quantity of no-carrier-added [(11)C]cyanide as radio-precursor. Based upon a reported synthesis of 2-(2-nitrophenyl)acetonitrile (), a highly reactive substrate 2-nitrobenzyl bromide () was evaluated for nucleophilic [(11)C]cyanation. Additionally, related reaction conditions were explored with the goal of obtaining of highly reactive 2-(2-nitrophenyl)-[1-(11)C]acetonitrile () while inhibiting its rapid conversion to 2,3-bis(2-nitrophenyl)-[1-(11)C]propanenitrile (). Next, a RANEY® Nickel catalyzed reductive cyclization method was utilized for synthesizing the desired [2-(11)C]indole with h…

Palladium nanoparticles–polypyrrole composite as an efficient catalyst for cyanation of aryl halides

2014

Abstract New palladium-polypyrrole (Pd/PPy) nanocomposites have been studied in cyanation of aryl halides with K 4 Fe(CN) 6 and showed high catalytic efficiency. Aryl iodides, bromides, and chlorides are active. The reaction can be performed both in organic solvents and in water; in the latter case, the catalyst was immobilized on graphite support. The cyanation of inactivated aryl chlorides is of special importance as only a few publications dealing with efficient cyanation of aryl chlorides are available, in which expensive and poisonous phosphine ligands and non-aqueous solvents are used. The influence of the morphology of the catalyst on its efficiency in cyanation was investigated, and…

Non-toxic cyanide sources and cyanating agents

2018

The present review gives an overview over non-toxic cyanation agents and cyanide sources used in the synthesis of structurally diverse products containing the nitrile function. Nucleophilic as well as electrophilic agents/systems that transfer the entire CN-group were taken in consideration. Reactions in which a preexisting carbon functionality is transformed into a nitrile function by addition of nitrogen are however not covered here.

Synthesis of α-aminonitriles using aliphatic nitriles, α-amino acids, and hexacyanoferrate as universally applicable non-toxic cyanide sources

2018

In cyanation reactions, the cyanide source is often directly added to the reaction mixture, which restricts the choice of conditions. The spatial separation of cyanide release and consumption offers higher flexibility instead. Such a setting was used for the cyanation of iminium ions with a variety of different easy-to-handle HCN sources such as hexacyanoferrate, acetonitrile or α-amino acids. The latter substrates were first converted to their corresponding nitriles through oxidative decarboxylation. While glycine directly furnishes HCN in the oxidation step, the aliphatic nitriles derived from α-substituted amino acids can be further converted into the corresponding cyanohydrins in an oxi…

Synthesis of l -[4-11 C]Asparagine by Ring-Opening Nucleophilic 11 C-Cyanation Reaction of a Chiral Cyclic Sulfamidate Precursor

2018

The development of a convenient and rapid method to synthesize radiolabeled, enantiomerically pure amino acids (AAs) as potential positron emission tomography (PET) imaging agents for mapping various biochemical transformations in living organisms remains a challenge. This is especially true for the synthesis of carbon-11-labeled AAs given the short half-life of carbon-11 (11 C, t1/2 =20.4 min). A facile synthetic pathway to prepare enantiomerically pure 11 C-labeled l-asparagine was developed using a partially protected serine as a starting material with a four-step transformation providing a chiral five-membered cyclic sulfamidate as the radiolabeling precursor. Its structure and absolute…

Enantioselective Organocatalysis of Strecker and Mannich Reactions Based on Carbohydrates.

2007

Efficient organocatalysts for enantioselective Strecker and Mannich reactions were constructed from glucosamine as a readily accessible chiral scaffold. A variety of aromatic aldimines were subjected to hydrocyanation with good to excellent yield (72–98 %) and, in part, high enantioselectivity (69–95 % ee). Influence of the catalyst architecture on the enantioselectivity obviously arises from restrictions imposed on the conformational flexibility of the monosaccharidic backbone. In the asymmetric Mannich reaction moderate yields (up to 76 %) and enantioselectivities (up to 58 % ee) have been achieved with the described catalyst.

On the Unique Reactivity of Pd(OAc)2with Organic Azides: Expedient Synthesis of Nitriles and Imines

2013

Organic azides are well-established as versatile compounds that can act as precursors of different heterocycles (triazoles, triazolines, tetrazoles, etc.) or other nitrogen-containing compounds, such as amines (Staudinger reduction, Curtius rearrangement) or imines (Schmidt rearrangement, aza-Wittig reaction).1 Besides the ubiquitous copper-catalysed azide–alkyne cycloaddition reaction,2 two applications of organic azides have recently attracted the interest of the synthetic community: 1) the preparation of aziridines through the generation of nitrenes3 and 2) the synthesis of nitriles. We were particularly interested in the latter application, owing to the importance of the cyano group in …