Categories: C=C Bond Formation >
Synthesis of 1,3-enynes by olefination
Deprotonation of 3,3,3-trichloropropyl-1-triphenylphosphonium chloride generates the corresponding phosphorane, which reacts with aldehydes to give trichloromethylated (Z)-olefins, which are useful for the synthesis of (Z)-1,3-enynes, (Z,Z)-1-chloro-1,3-dienes, and 1,3-diynes in high yields and stereospecificities.
M. S. Karatholuvhu, P. L. Fuchs, J. Am. Chem. Soc., 2004, 126, 14314-14315.
A 1,2,3-triazole-promoted iron(III)-catalyzed propargyl alcohol dehydration enables the synthesis of conjugated enynes in good to excellent yields with a large substrate scope and excellent stereoselectivity (only Z-isomers).
W. Yan, X. Ye, N. G. Akhmedov, J. L. Petersen, X. Shi, Org. Lett., 2012, 14, 2358-2361.
Hot water as a mildly acidic catalyst efficiently promoted 1,n-rearrangement (n = 3, 5, 7, 9) of allylic alcohols. In some cases, the rearrangement reactions joined isolated C-C double or triple bonds to generate conjugated polyene or enyne structure motifs. The polyene natural product navenone B has been constructed by iterative use of a Grignard reaction, a 1,3-rearrangement of the resulting allylic alcohol, and subsequent oxidation.
P.-F. Li, H.-L. Wang, J. Qu, J. Org. Chem., 2014, 79, 3955-3962.