1,2-ダイオルのニッケル触媒による選択的モノアミネーション:アミノアルコールへの手頃なアプローチ
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The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
The reaction is catalyzed by amine base, which abstracts the acidic α hydrogen of the activated methylene to generate a resonance stabilized enolate ion. The basic strength of the amine is insufficient to form the enolate of aldehydes or ketones. However, it acts as a nucleophile that attacks the carbonyl...
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
The reaction proceeds via abstraction of the acidic α hydrogen from a ꞵ-diester to produce a doubly stabilized enolate ion. The nucleophilic enolate attacks the alkyl halide in an SN2 manner to form an alkylated malonic ester intermediate with a new C–C bond. Further treating the intermediate with aqueous acid or base results in...
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.
Reductive amination using sodium cyanoborohydride as the reducing agent is called the Borch reaction. Sodium cyanoborohydride is a mild...
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.
Figure 1: The base-catalyzed aldol addition reaction of aldehydes.
The reaction preferentially occurs with simple aldehydes, where the α carbon is monosubstituted. The equilibrium of the reaction involving disubstituted aldehydes and ketones shifts backward to the reactants due to the steric interactions at the α carbon. The...
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...

