Main Article Content
Abstract
The stereodefined synthesis of 1,3-alkenynes based on in situ generated stereodefined alkenylcopper reagents is presented. The hydroboration of alkynes with dibromoborane-methyl sulfide complex followed by treatment with trimethylene glycol provides stable (E)-1-alkenylboronate esters. These boronate esters readily undergo “ate” complexes with a hindered base such as potassium-tbutoxide. The transmetalation of the alkenyl group from boron to copper via the “ate” complexes retains the original stereochemistry defined from the starting alkenylboronate esters. The effect of representative bases on stereodefined alkenylboronate esters and subsequent reaction of these boronate esters in the transmetalation reaction with copper(I) bromide-methyl sulfide is investigated. The resulting stereodefined alkenylcopper species generated in situ readily couple with 1-bromo-1-alkynes to give the corresponding 1,3-alkenynes with retention of stereochemistry. Since (Z)-1-alkenylboronate esters are easily accessible, both cis and trans isomeric 1,3-alkenynes are synthesized.
Keywords
Article Details
References
- J.N. Labovitz, C.A. Henrick and V.L. Corbin, Tetrahedron Lett., 16, 4209 (1975); https://doi.org/10.1016/S0040-4039(00)91150-X.
- C.A. Henrick, Tetrahedron, 33, 1845 (1977); https://doi.org/10.1016/0040-4020(77)80372-4.
- H.C. Brown and G. Zweifel, J. Am. Chem. Soc., 83, 3834 (1961); https://doi.org/10.1021/ja01479a024.
- C. Descoins and D. Samain, Tetrahedron Lett., 17, 745 (1976); https://doi.org/10.1016/S0040-4039(00)77940-8.
- R.F. Garwood, E. Osakay and B.C.L. Weedon, Chem. Ind., 1684 (1962).
- E. Negishi, G. Lew and T. Yoshida, J. Chem. Soc. Chem. Commun., 874 (1973); https://doi.org/10.1039/c39730000874.
- E. Negishi and A. Abramovitch, Tetrahedron Lett., 18, 411 (1977); https://doi.org/10.1016/S0040-4039(01)92652-8.
- N. Miyaura, K. Yamada and A. Suzuki, Tetrahedron Lett., 20, 3437 (1979); https://doi.org/10.1016/S0040-4039(01)95429-2.
- H.C. Brown and J.B. Campbell Jr., J. Org. Chem., 45, 550 (1980); https://doi.org/10.1021/jo01291a046.
- H.C. Brown and G.A. Molander, J. Org. Chem., 46, 645 (1981); https://doi.org/10.1021/jo00316a037.
- H.C. Brown, N.G. Bhat and V. Somayaji, Organometallics, 2, 1311 (1983); https://doi.org/10.1021/om50004a008.
- H.C. Brown and T. Imai, Organometallics, 3, 1392 (1984); https://doi.org/10.1021/om00087a013.
References
J.N. Labovitz, C.A. Henrick and V.L. Corbin, Tetrahedron Lett., 16, 4209 (1975); https://doi.org/10.1016/S0040-4039(00)91150-X.
C.A. Henrick, Tetrahedron, 33, 1845 (1977); https://doi.org/10.1016/0040-4020(77)80372-4.
H.C. Brown and G. Zweifel, J. Am. Chem. Soc., 83, 3834 (1961); https://doi.org/10.1021/ja01479a024.
C. Descoins and D. Samain, Tetrahedron Lett., 17, 745 (1976); https://doi.org/10.1016/S0040-4039(00)77940-8.
R.F. Garwood, E. Osakay and B.C.L. Weedon, Chem. Ind., 1684 (1962).
E. Negishi, G. Lew and T. Yoshida, J. Chem. Soc. Chem. Commun., 874 (1973); https://doi.org/10.1039/c39730000874.
E. Negishi and A. Abramovitch, Tetrahedron Lett., 18, 411 (1977); https://doi.org/10.1016/S0040-4039(01)92652-8.
N. Miyaura, K. Yamada and A. Suzuki, Tetrahedron Lett., 20, 3437 (1979); https://doi.org/10.1016/S0040-4039(01)95429-2.
H.C. Brown and J.B. Campbell Jr., J. Org. Chem., 45, 550 (1980); https://doi.org/10.1021/jo01291a046.
H.C. Brown and G.A. Molander, J. Org. Chem., 46, 645 (1981); https://doi.org/10.1021/jo00316a037.
H.C. Brown, N.G. Bhat and V. Somayaji, Organometallics, 2, 1311 (1983); https://doi.org/10.1021/om50004a008.
H.C. Brown and T. Imai, Organometallics, 3, 1392 (1984); https://doi.org/10.1021/om00087a013.