Synthesis of Internal gem-Diborylalkanes by Copper-Catalyzed Double Hydroboration of Conjugated Internal Alkynes

Title:Synthesis of Internal gem-Diborylalkanes by Copper-Catalyzed Double Hydroboration of Conjugated Internal Alkynes

Volume: 14 Issue: 4

Author(s): Yuma Netsu and Naofumi Tsukada*

Affiliation:

• Department of Chemistry, Faculty of Science, Shizuoka University, Shizuoka 422-8529,Japan

Keywords: Copper, catalysis, hydroboration, alkyne, diboryl compound, conjugated carbonyl compound.

Abstract: Background: Geminal diboryl reagents have attracted considerable attention due to their unique reactivities. Double hydroboration of alkynes is a convenient and useful method for the synthesis of diborylalkanes. However, the double hydroboration is applied mainly to terminal alkynes.

Methods: Ethyl propiolate was treated with B2pin2 and methanol in the presence of various copper catalysts and ligands. The reaction of several internal conjugated alkynes was also investigated under the optimized reaction conditions.

Results: Geminal diboryl compounds were obtained in high yields. While 1,10-phenanthroline was more effective for the reaction of methyl propiolate than tri-n-butylphosphine, the divided addition of B2pin2 and the use of tri-n-butylphosphine were necessary for the reaction of several alkynes, for which second hydroboration was slower.

Conclusion: We have found that the copper-catalyzed double hydroboration of conjugated internal alkynes was a useful method for the synthesis of internal gem-diborylalkanes.

Cite this article as:

Netsu Yuma and Tsukada Naofumi *, Synthesis of Internal gem-Diborylalkanes by Copper-Catalyzed Double Hydroboration of Conjugated Internal Alkynes, Letters in Organic Chemistry 2017; 14 (4) . https://dx.doi.org/10.2174/1570178614666170321114445

DOI https://dx.doi.org/10.2174/1570178614666170321114445	Print ISSN 1570-1786
Publisher Name Bentham Science Publisher	Online ISSN 1875-6255