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•An anhydrous method for the synthesis of terminal alkynes.•It involves 1,1-dibromoalkenes and succinimide.•Succinimide acts as a nucleophile and proton donor.•Applied in the ...synthesis of broad spectrum of terminal alkynes.•Extended to internal alkynes synthesis under tandem conditions.
An easy synthetic method was developed under dry reaction conditions for the preparation of terminal alkynes from 1,1-dibromoalkenes and in the presence of succinimide which acts as a nucleophile and proton donor. It was demonstrated with the synthesis of a broad spectrum of terminal alkynes and extended to synthesize internal alkynes under tandem reaction conditions.
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•The hydrodebromination of 1,1-dibromoalkenes via visible light catalysis.•A new method for the synthesis of vinyl bromides derivatives.•Broad scope of the substrates, moderate to ...excellent yields, simple operation and mild conditions.
Vinyl bromides are versatile synthetic intermediates and widely applied in organic synthesis and pharmaceuticals. Herein, a hydrodebromination reaction of 1,1-dibromoalkenes was established via visible light catalysis. A variety of structurally different vinyl bromides were obtained in moderate to excellent yields.
Growing interest has been paid to bis(tricyclic) aromatic enes as key components of functional organic materials such as molecular switches and charge-transporting materials. Currently, the ...synthetic approaches to the overcrowded alkenes are limited to McMurry coupling and Barton–Kellog olefination. This communication reports that palladium-catalyzed double cross-coupling reaction of phenazastannines with 9-(dibromomethylene)fluorene, -xanthene, -thioxanthene, and -thioxanthene-S,S-dioxide serves as a facile synthetic approach to bis(tricyclic) aromatic enes such as 9-(9H-fluoren-9-ylidene)acridines, 9-(9H-oxanthen-9-ylidene)acridines, 9-(9H-thioxanthen-9-ylidene)acridines, and 9-(10,10-dioxido-9H-thioxanthen-9-ylidene)acridines.
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Pd-catalyzed domino synthesis of 1,3-diynes was accomplished using 1,1-dibomoalkenes under copper-free coupling conditions. This domino procedure involves base mediated in situ ...generation of 1-bromoalkyne and its subsequent coupling to give 1,3-diyne. The optimized copper-free coupling method afforded good to high yields of symmetrical 1,3-diynes in a one-pot operation.
The nucleophilic reactivity of 1,8‐diazabicyclo5.4.0undec‐7‐ene (DBU) was completely controlled by the formation of monohydrate (DBU⋅H2O) in the synthesis of 1‐(bromoethynyl)arenes from ...1,1‐dibromoalkenes. Differential reactivity of DBU in protic solvents as compared to aprotic solvents has been explored to prevent the formation of mixtures of products in this reaction. Hydrated DBU is found to be superior to dry DBU, both for the selective synthesis and ease of isolation. In addition, use of DBU⋅H2O as a non‐nucleophilic mild base allowed us to synthesise 1‐(bromoethynyl)arenes via a reaction under solvent‐free conditions. Utilization of DBU⋅H2O as sole reagent also allowed us to isolate the products without column chromatographic purifications.
A protocol for the one-pot synthesis of internal alkynes from 1,1-dibromoalkenes is reported. The method is hinged upon the Suzuki–Miyaura cross-coupling of 2-aryl- or 2-heteroaryl-1,1-dibromoalkenes ...with aryl or heteroaryl boronic acids or borate esters followed by dehydrobromination of the intermediate coupled products. Yields up to 89% were obtained.
Catalytic olefination of carbonyl steroid derivatives were used to obtain the corresponding 1,1-dibromoalkenes. For this,
N
-unsubstituted steroid hydrazones were involved into the reaction with ...tetrabromomethane in the presence of copper(
i
) chloride. The dibromides can be used for the synthesis of various functionalized steroids by conversion of a dibromomethylidene fragment to the carboxy, amide, and phosphonate groups.
Vinyl bromides
2a–f, useful intermediates in organic synthesis, have been obtained under mild conditions and in good yields via electrochemical reduction of 1,1-dibromoalkenes
1a–f (readily available ...substrates). The reduction has been carried out in MeCN–tetraethylammonium perchlorate (TEAP) solutions, in the presence of a proton donor, at a Au, Hg, C or Ag cathode. The use of specific reducing agents, catalysts and bases, employed in the classical procedures, has been avoided. The isomeric
E/
Z ratio in vinyl bromides
2a–f is affected by the cathode material.
Palladium catalyzed bis-Suzuki coupling reactions of 2-trifluoromethyl-1,1-dibromoalkenes with aryl and hetero-aryl boronic acids afford 2-trifluoromethyl tetra-substituted alkenes in excellent ...yield.
Palladium catalyzed bis-Suzuki coupling reactions of 2-trifluoromethyl-1,1-dibromoalkenes with aryl and hetero-aryl boronic acids afford 2-trifluoromethyl tetra-substituted alkenes in excellent yield.
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