Synthesis 2011(23): 3839-3847  
DOI: 10.1055/s-0030-1260253
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Homo- and Heterocoupling of Terminal Conjugated Enynes: One-Pot Synthesis of Alka-1,7-diene-3,5-diynes and Alk-1-ene-3,5-diynes via Two Types of Coupling Reaction

Masayuki Hoshi*, Mitsuhiro Okimoto, Shingo Nakamura, Shinya Takahashi
Department of Biotechnology and Environmental Chemistry, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507, Japan
Fax: +81(157)247719; e-Mail: hoshi-m@chem.kitami-it.ac.jp;
Further Information

Publication History

Received 1 August 2011
Publication Date:
05 October 2011 (online)

Abstract

Conjugated dienediynes and enediynes with definite geometry­ have been prepared in a one-pot manner. This protocol involves two types of coupling reaction, a Suzuki-type coupling and either a Hay coupling or a Cadiot-Chodkiewicz coupling. Thus, the copper-mediated cross-coupling reaction of (E)-alk-1-enyldisiamylborane with (trimethylsilyl)ethynyl bromide is carried out in the presence of 1 M NaOMe to generate (E)-alk-3-en-1-yne, which is subjected to either palladium/copper-catalyzed homocoupling in the presence of DABCO or copper-catalyzed heterocoupling with 1-iodoalk-1-yne in the presence of TBD or pyrrolidine in a single reaction pot without isolating (E)-alk-3-en-1-yne. The homocoupling has realized the stereoselective construction of (1E,7E)-alka-1,7-diene-3,5-diynes, and the heterocoupling has achieved the formation of (E)-alk-1-ene-3,5-diynes. In addition, starting from (Z)-alk-1-enyldisiamylborane instead of the E-isomer, this series of reactions has led to the formation of (1Z,7Z)-alka-1,7-diene-3,5-diynes and (Z)-alk-1-ene-3,5-diynes, albeit limiting the scope of the substrate.

15

Compound 2a was formed in about 75% GC yield based on Me3SiCºCBr used; unpublished results.

16

In the original procedure ethyl bromoacetate was used as the oxidant.

18

Compounds 5a and 5b were formed in 72-75% GC yield based on Me3SiCºCBr used; unpublished results.