Categories: CC Bond Formation >
Synthesis of haloalkynes
Reaction of readily accessible benzylic and allylic alkyl bromides with iodoform followed by a one-pot double elimination procedure enables a triphenylphosphine-free synthesis of 1-iodoalkynes including facile purification compared with Corey-Fuchs iodoalkynylation conditions. Replacing CHI3 with CHI2Cl allows the isolation of gem-(Z)-chloro-(E)-iodoalkenes. The use of benzhydryl bromides as nucleophiles leads to trisubstituted alkenes.
G. Pelletier, S. Lie, J. J. Mousseau, A. B. Charette, Org. Lett., 2012, 14, 5464-5467.
Tetra-n-butylammonium is a mild and efficient base for the elimination of bromoalkenes. Treatment of 1,1-dibromoalkenes, (Z)-1-bromoalkenes, and internal bromoalkenes with 5 equiv of TBAF • 3 H2O in DMF yielded terminal and internal alkynes in high yields without problems regarding the presence of water.
M. Okutani, Y. Mori, J. Org. Chem., 2009, 74, 442-444.
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.