Gallium(III)-Promoted Halocyclizations of 1,6-Diynes
Kyle R Strom1, Anna C Impastato1, Kenneth J Moy1
1Department of Chemistry Boston University, Boston, Massachusetts 02215, United States.
Organic Letters
|April 18, 2015
Summary
Gallium(III) halides efficiently cyclize 1,6-diynes into vinyl halides. Acidic conditions enable further Friedel-Crafts reactions, yielding iodoindenopyridines, useful in cross-coupling reactions.
Area of Science:
- Organic Chemistry
- Organometallic Chemistry
Background:
- 1,6-diynes are versatile precursors in organic synthesis.
- Developing efficient cyclization methods for diynes is crucial for accessing complex molecular architectures.
Purpose of the Study:
- To investigate the cyclization of 1,6-diynes using stoichiometric gallium(III) halides.
- To explore the subsequent transformations of the cyclization products under acidic conditions.
- To evaluate the utility of the synthesized vinyl halides in cross-coupling reactions.
Main Methods:
- Stoichiometric cyclization of 1,6-diynes with gallium(III) halides.
- Acid-catalyzed in situ Friedel-Crafts cyclization of intermediate vinyl halides.
- Application of vinyl halides in palladium-catalyzed cross-coupling reactions.
Main Results:
- Vinyl halides were synthesized in good to excellent yields from 1,6-diynes.
- Iodoindenopyridines were accessed through in situ Friedel-Crafts cyclization of iodocyclization products.
- The synthesized vinyl halides demonstrated utility in subsequent cross-coupling reactions.
Conclusions:
- Stoichiometric Ga(III) halides provide an effective method for the cyclization of 1,6-diynes.
- The developed methodology allows for the synthesis of vinyl halides and complex iodoindenopyridines.
- The study highlights the synthetic potential of Ga(III)-mediated cyclizations and subsequent transformations.
More Related Videos
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
Related Concept Videos
02:34Preparation of Alkynes: Dehydrohalogenation
18.9K
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
18.9K
02:38Electrophilic Addition to Alkynes: Halogenation
10.6K
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
10.6K
01:14Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
4.0K
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.
4.0K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
14.4K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
14.4K
01:20Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
2.7K
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...
2.7K
01:16Cycloaddition Reactions: Overview
3.8K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
3.8K