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The Hofmann–Martius rearrangement in organic chemistry is a rearrangement reaction converting an N-alkylated aniline to the corresponding ortho and / or para aryl-alkylated aniline. The reaction requires heat, and the catalyst is an acid like hydrochloric acid. [1] [2]
The Hofmann rearrangement (Hofmann degradation) is the organic reaction of a primary amide to a primary amine with one less carbon atom. [ 1 ] [ 2 ] [ 3 ] The reaction involves oxidation of the nitrogen followed by rearrangement of the carbonyl and nitrogen to give an isocyanate intermediate.
Example mechanism for alkyne zipper reaction. The 3-aminopropylamine anion attacks the same lesser-substituted carbon adjacent to the allene , removing a proton and catalyzing a similar process, where the electrons from the carbon-hydrogen bond move to form a triple-bond (an alkyne ).
The reaction mechanism is that of the related Hofmann degradation. [2] Weermann degradation 1st unsattuered. At first the carbonic acid amide (1) reacts with the sodium hypochlorite. After separate water and chloride an amine with a free bond is built 2. The intermediate (3) is generated by rearrangement. At this point two different mechanisms ...
The rule states that with the addition of a protic acid HX or other polar reagent to an asymmetric alkene, the acid hydrogen (H) or electropositive part gets attached to the carbon with more hydrogen substituents, and the halide (X) group or electronegative part gets attached to the carbon with more alkyl substituents.
The rearrangement is widely used in organic synthesis. It is symmetry-allowed when it is suprafacial on all components. The transition state of the molecule passes through a boat or chair like transition state. An example of the Cope rearrangement is the expansion of a cyclobutane ring to a cycloocta-1,5-diene ring:
The Dieckmann method is practical only for 5- to 8-membered rings (with modest yields for 7- and 8-membered). The Thorpe method is more easily modified via high dilution (e.g., 0.001 M in benzene/ether) to enable the synthesis of large rings, but 4-membered and 9- to 13-membered rings are still not accessible.
An example of an application of the Cook-Heilbron thiazole synthesis. Illustrates the synthesis of 2-methyl-5-aminothiazoles were prepared via condensation and cyclization of aminoacetonitrile and ethyldithioacetate as part of an approach to synthesize pyridyl and thiazoyl bisamide CSF-1R inhibitors for use in novel cancer therapeutics.