Related Experiment Video
Updated: Jun 8, 2026
09:45
A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Microwave alkylation of lithium tetrazolate
Danny Müller1, Christian Knoll1, Peter Weinberger1
1Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria.
Monatshefte Fur Chemie
|January 28, 2017
Summary
A new method for synthesizing N1-substituted tetrazoles was developed using lithium tetrazolate alkylation. This approach enhances substrate scope and suppresses N1-N2 isomerism, yielding pure N1-substituted products for coordination chemistry.
Area of Science:
- Coordination Chemistry
- Organic Synthesis
- Materials Science
Background:
- N1-substituted tetrazoles are crucial ligands in transition metal coordination chemistry, particularly for spin crossover materials.
- Traditional synthesis methods like the Franke-synthesis have limitations in substrate scope.
- Controlling N1-N2 isomerism during tetrazole functionalization is a persistent synthetic challenge.
Purpose of the Study:
- To develop a novel, more flexible synthetic protocol for N1-substituted tetrazoles.
- To overcome the limitations of existing methods for tetrazole functionalization.
- To achieve regioselective N1-alkylation, avoiding undesired N1-N2 isomers.
Main Methods:
- Alkylation of lithium tetrazolate with various alkyl bromides.
- Optimization of reaction conditions, including solvent composition (30 vol.% aqueous ethanol).
- Utilizing highly pure lithium tetrazolate to ensure regioselectivity.
Main Results:
- A new protocol for the synthesis of N1-substituted tetrazoles via direct alkylation was established.
- N1-N2 isomerism was successfully suppressed, leading to exclusively N1-substituted products.
- The method demonstrated broad substrate scope, confirmed by successful synthesis with diverse alkyl bromides.
Conclusions:
- The developed alkylation protocol offers enhanced flexibility and control for synthesizing N1-substituted tetrazoles.
- This method provides a reliable route to pure N1-substituted tetrazoles, valuable for spin crossover applications.
- The findings open new avenues for designing functional tetrazole-based ligands for coordination chemistry.
More Related Videos
Related Concept Videos
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
01:19Acid Halides to Alcohols: LiAlH4 Reduction
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
01:14Acid Halides to Ketones: Gilman Reagent
Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
01:10α-Alkylation of Ketones via Enolate Ions
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...
01:15Acid Halides to Alcohols: Grignard Reaction
Organomagnesium halides, commonly known as Grignard reagents, convert acid halides to tertiary alcohols. The reaction requires two equivalents of the Grignard reagent and proceeds via a ketone intermediate.
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.