Pd(0)-catalyzed selective [2 + 2 + 2] cycloaddition of dimethyl nona-2,7-diyne-1,9-dioate derivatives with dimethyl acetylenedicarboxylate
作者:Yoshihiko Yamamoto、Asako Nagata、Kenji Itoh
DOI:10.1016/s0040-4039(99)00927-2
日期:1999.7
In the presence of 2.5 mol % of Pd2(dba)3 and 5 mol % of PPh3, nearly equimolar amounts of dimethyl nona-2,7-diyne-1,9-dioate derivatives and dimethylacetylenedicarboxylate (DMAD) were reacted in toluene at 110 °C to give indan, phthalin, and isoindoline derivatives selectively in moderate to good yields. The competing homo-couplings of both the diynediesters and DMAD were completely suppressed. The
of these intramolecular alkyne cyclotrimerizations, stoichiometric reactions of [Pd(2)(dba)(3)] with a diyne diester and a triyne diester bearing ether tethers were conducted in acetone at room temperature to furnish an oligomeric bicyclopalladacyclopentadiene and a Pd(0) triyne complex, respectively. The structures of these novel complexes were unequivocally determined by Xray structure analysis.
Synthesis of Perfluoroalkylated Benzenes and Pyridines through Cationic Rh(I)/Modified BINAP-Catalyzed Chemo- and Regioselective [2 + 2 + 2] Cycloaddition
A convenient synthesis of perfluoroalkylated benzenes and pyridines has been achieved by a cationic Rh(I)/modified BINAP-complex-catalyzed chemo- and regioselective [2 + 2 + 2] cycloaddition of alkynes with a perfluoroalkylacetylene and a perfluoroalkylnitrile.
Rhodium-Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of α,ω-Diynes with Unsymmetrical 1,2-Disubstituted Alkenes
bisphosphine complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition of α,ω-diynes with electron-rich and unstrained unsymmetrical 1,2-disubstituted alkenes to give chiral multicyclic compounds with good yields and ee values. Interestingly, enantioselectivity highly depends on the structures of α,ω-diynes used presumably due to the presence of two distinct reaction pathways.