Commercially available liquid enol ethers and acetates as gaseous alkyne equivalents in cationic Rh(I)/BINAP-catalyzed chemo- and regioselective formal cross-alkyne cyclotrimerizations
作者:Hiromi Hara、Masao Hirano、Ken Tanaka
DOI:10.1016/j.tet.2009.02.047
日期:2009.6
A cationicrhodium(I)/BINAPcomplex catalyzes partial intramolecular [2+2+2] cycloadditions of 1,6- and 1,7-diynes with enol ethers or a ketene acetal giving substituted benzenes in good yields. The same catalyst also catalyzes complete intermolecular [2+2+2] cycloadditions of two different monoynes with enol acetates giving tri- and tetrasubstituted benzenes in good yields with complete regioselectivity
Bridging a gap: A cationic rhodium(I)/ligand complex catalyzes the title reaction of alkynes and amide‐linked 1,5‐dienes, leading to bridged multicyclic compounds, with high chemo‐, regio‐, and enantioselectivity (see scheme; Bn=benzyl).
We have determined that a cationicrhodium(I)/BINAPcomplex catalyzes a [2+2+2] cycloaddition of 1,6-diynes with a protected dehydroamino acid, leading to protected α-amino acids bearing a quaternary carbon center in high yield with high enantioselectivity.