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Key step in synthesis of lithospermic acid. The total synthesis of calothrixin A and B features an intramolecular Pd-catalyzed cross coupling reaction via C-H activation, an example of a guided C-H activation. Cross coupling occurs between aryl C-I and C-H bonds to form a C-C bond. [31]
In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new carbon-carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction. [1] [2] [3]
For example, protonation of methanol gives an electrophilic methylating reagent that reacts by the S N 2 pathway: CH 3 OH + H + → [CH 3 OH 2] + Similarly, methyl iodide and methyl triflate are viewed as the equivalent of the methyl cation because they readily undergo S N 2 reactions by weak nucleophiles. The methyl cation has been detected in ...
In radical disproportionation reactions one molecule acts as an acceptor while the other molecule acts as a donor. [2] In the most common disproportionation reactions, a hydrogen atom is taken, or abstracted by the acceptor as the donor molecule undergoes an elimination reaction to form a double bond. [3]
[1] [2] Mechanism of one type of carbonyl addition hydrogen auto-transfer reaction involving hydrometalation (step 2). [3] Hydrogen auto-transfer, also known as borrowing hydrogen, is the activation of a chemical reaction by temporary transfer of two hydrogen atoms from the reactant to a catalyst and return of those hydrogen atoms back to a ...
Occasionally, an aldol condensation is buried in a multistep reaction or in catalytic cycle as in the following example: [18] Ru Catalyzed Cyclization of Terminal Alkynals to Cycloalkenes. In this reaction an alkynal 1 is converted into a cycloalkene 7 with a ruthenium catalyst and the actual condensation takes place with intermediate 3 through 5.
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In chemistry, the carbon–hydrogen bond (C−H bond) is a chemical bond between carbon and hydrogen atoms that can be found in many organic compounds. [1] This bond is a covalent, single bond, meaning that carbon shares its outer valence electrons with up to four hydrogens. This completes both of their outer shells, making them stable. [2]