4.3. Reaction Mechanism 2373 4.4. Asymmetric Synthesis 2374 4.5. Outlook 2374 5. Alternating Polymerization of Oxiranes and CO2 2374 5.1. Reaction Outlines 2374 5.2. Catalyst 2376 5.3. Asymmetric Polymerization 2377 5.4. Immobilized Catalysts 2377 6. Synthesis of Urea and Urethane Derivatives 2378 7. Synthesis of Carboxylic Acid 2379 8. Synthesis of Esters and Lactones 2380 9. Synthesis of Isocyanates 2382 10. Hydrogenation and Hydroformylation, and Alcohol Homologation 2382

Transformation of carbon dioxide.

Direct C-H transformation via iron catalysis.

Hydrogen autotransfer in the N-alkylation of amines and related compounds using alcohols and amines as electrophiles.

Synthesis of Heterocycles via Palladium-Catalyzed Carbonylations

Alcohols can be temporarily converted into carbonyl compounds by the metal-catalysed removal of hydrogen. The carbonyl compounds are reactive in a wider range of transformations than the precursor alcohols and can react in situ to give imines, alkenes, and α-functionalised carbonyl compounds. The metal catalyst, which had borrowed the hydrogen, then returns it to the transformed carbonyl compound, leading to an overall process in which alcohols can be converted into amines, compounds containing CC bonds and β-functionalised alcohols.

Borrowing hydrogen in the activation of alcohols

Synthesis of secondary amines

A novel method for the mono-N-alkylation of primary amines, diamines, and polyamines was developed using cesium bases in order to prepare secondary amines efficiently. A cesium base not only promoted alkylation of primary amines but also suppressed overalkylations of the produced secondary amines. Various amines, alkyl bromides, and alkyl sulfonates were examined, and the results demonstrated this methodology was highly chemoselective to favor mono-N-alkylation over dialkylation. In particular, use of either sterically demanding substrates or amino acid derivatives afforded the secondary amines exclusively, offering wide applications in peptidomimetic syntheses.

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Cesium effect: high chemoselectivity in direct N-alkylation of amines

Perspectives on Alkyl Carbonates in Organic Synthesis

Efficient carbamate synthesis via a three-component coupling of an amine, CO2, and alkyl halides in the presence of Cs2CO3 and tetrabutylammonium iodide.

Ralph N. Salvatore

Papers

Synthesis of secondary amines

Cesium effect: high chemoselectivity in direct N-alkylation of amines

Perspectives on Alkyl Carbonates in Organic Synthesis

Efficient carbamate synthesis via a three-component coupling of an amine, CO2, and alkyl halides in the presence of Cs2CO3 and tetrabutylammonium iodide.

Cesium Hydroxide Promoted Chemoselective N-Alkylation for the Generally Efficient Synthesis of Secondary Amines