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Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction

Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction

α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.

SN2 Reaction: Stereochemistry

S_N2 Reaction: Stereochemistry

In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...

E1 Reaction: Stereochemistry and Regiochemistry

E1 Reaction: Stereochemistry and Regiochemistry

One of the critical aspects of the E1 reaction mechanism, as also observed in E2, is the regiochemistry, with multiple regioisomers obtained as products. In the example discussed, the presence of water as a weak base favors elimination over substitution to generate two alkenes. Given that alkenes’ stability increases with the number of alkyl groups across the double bond, typically, E1 reactions lead to the Zaitsev product, for this is more substituted and stable than the Hofmann product.

E2 Reaction: Stereochemistry and Regiochemistry

E2 Reaction: Stereochemistry and Regiochemistry

Elimination reactions of alkyl halides can yield one or more alkenes depending on the specific regiochemical and stereochemical considerations. While the regiochemistry of the reaction governs the location of the double bond in the product, the stereochemical requirements often influence the geometry.
When a substrate with two different β hydrogens undergoes an E2 elimination, the presence of a strong base can yield two regioisomeric alkenes. The more-substituted alkene is the major...

Polymer Classification: Stereospecificity

Polymer Classification: Stereospecificity

Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...

SN2 Reaction: Kinetics

S_N2 Reaction: Kinetics

Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...

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Related Experiment Video

Updated: Jun 24, 2025

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

Published on: February 6, 2019

Comparing search algorithms on the retrosynthesis problem.

Milo Roucairol¹, Tristan Cazenave¹

¹LAMSADE, Université Paris Dauphine - PSL, Paris, France.

Molecular Informatics

|June 12, 2024

Summary

This summary is machine-generated.

New algorithms, Nested Monte Carlo Search and Greedy Best First Search, outperformed the standard Monte Carlo Tree Search in retrosynthesis prediction using AiZynthFinder. Further improvements depend on enhancing the policy network quality.

Keywords:

MCTS Monte Carlo Tree Search retrosynthesis search algorithm

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Curation of Computational Chemical Libraries Demonstrated with Alpha-Amino Acids

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Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Published on: September 12, 2018

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Last Updated: Jun 24, 2025

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

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Published on: February 6, 2019

Curation of Computational Chemical Libraries Demonstrated with Alpha-Amino Acids

Curation of Computational Chemical Libraries Demonstrated with Alpha-Amino Acids

Published on: April 13, 2022

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Published on: September 12, 2018

Area of Science:

Computational chemistry
Artificial intelligence in drug discovery

Background:

Retrosynthesis is crucial for synthetic route planning.
AiZynthFinder is an open-source tool for retrosynthetic analysis.
Evaluating and improving search algorithms within AiZynthFinder is essential for its effectiveness.

Purpose of the Study:

To compare the performance of Nested Monte Carlo Search (NMCS) and Greedy Best First Search (GBFS) against the base Monte Carlo Tree Search (MCTS) in AiZynthFinder.
To assess the impact of different search algorithms on the accuracy and efficiency of retrosynthetic predictions.
To identify limitations and future directions for improving AiZynthFinder's search capabilities.

Main Methods:

Implementation and testing of NMCS and GBFS algorithms within the AiZynthFinder framework.
Utilizing a benchmark dataset curated from the PubChem database by Bayer chemists.
Comparative analysis of NMCS, GBFS, and base MCTS performance metrics.

Main Results:

Both NMCS and GBFS demonstrated superior performance compared to the base MCTS in retrosynthetic prediction.
NMCS showed a slight advantage over GBFS, particularly when experimenting with a playout heuristic.
The performance of all tested search algorithms was found to be constrained by the quality of the underlying policy network.

Conclusions:

NMCS and GBFS represent significant improvements over the standard MCTS for retrosynthesis using AiZynthFinder.
Enhancing the policy network is identified as the critical next step for further improving prediction accuracy.
The study provides valuable insights into optimizing AI-driven retrosynthetic planning tools.