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In the gas phase, the comproportionation reaction is much faster because of the much higher mobility of the reacting species as illustrated, e.g., in the Claus reaction where H 2 S and SO 2 react together to form elemental sulfur. Various classical comproportionation reactions are detailed in the series of examples here below.
Using the twenty natural amino acids, for example, in a tripeptide creates 8,000 (20 3) possibilities. Solid-phase methods for small molecules were later introduced and Furka devised a "split and mix" approach [2] [4] In its modern form, combinatorial chemistry has probably had its biggest impact in the pharmaceutical industry. [5]
The Ugi reaction has been applied in combination with an intramolecular Diels-Alder reaction [16] in an extended multistep reaction. A reaction in its own right is the Ugi–Smiles reaction with the carboxylic acid component replaced by a phenol. In this reaction the Mumm rearrangement in the final step is replaced by the Smiles rearrangement. [17]
In organic chemistry, a cross-coupling reaction is a reaction where two different fragments are joined. Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reaction type is this:
These strategies can be grouped into approaches for managing reaction sequences. Reaction Sequences: Multistep synthesis involves sequential chemical reactions, each requiring its own work-up to isolate intermediates before proceeding to the next stage. [4] For example, the synthesis of paracetamol typically requires three separate reactions.
A multi-component reaction (or MCR), sometimes referred to as a "Multi-component Assembly Process" (or MCAP), is a chemical reaction where three or more compounds react to form a single product. [1] By definition, multicomponent reactions are those reactions whereby more than two reactants combine in a sequential manner to give highly selective ...
Nef reaction in combination with Michael addition. In carbohydrate chemistry, they are a chain-extension method for aldoses, as in the isotope labeling of C 14-D‑mannose and C 14-D‑glucose from D‑arabinose and C 14 ‑nitromethane (the first step here is a Henry reaction): The Nef reaction: chain extension. The opposite reaction is the ...
The Passerini reaction is often used in combinatorial and medicinal chemistry with recent utility in green chemistry and polymer chemistry. [ 6 ] [ 8 ] [ 9 ] As isocyanides exhibit high functional group tolerance, chemoselectivity , regioselectivity , and stereoselectivity , the Passerini reaction has a wide range of synthetic applications.