H. Dieck, C. Munz, C. Müller
Feb 27, 1990
Citations
0
Influential Citations
49
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Bis(dibenzylidene acetone)palladium reacts readily with N-aryl diazadienes (dad ArNCRCRNAr) and two moles of dialkyl acetylenedicarboxylates ECCE (E COOR) to form the palladacyclopentadienes (dad)PdCECECECE (2a–h). With a propiolic ester HCCE the corresponding complex (dad)PdCHCECECH 3 is also formed in small yield. An η2-alkyne complex 4 is obtained from the very bulky dad tBuNCHCHNtBu. The platinacyclopentadiene analogues of 2, (dad)PtCECECECE (5) have been prepared, but unlike the others are inactive in catalysis. The acetylenic diesters readily undergo cyclotrimerization with 2 as catalyst. Depending on the nature of the substituents, numerous alkynes R′CCR″ undergo a catalytic cyclo-cotrimerization with two moles of the diester ECCE to form a number of interestingly substituted benzenes. In the case of propargylic alcohols benzolactones are formed via a transesterification reaction during the catalysis. For phenylacetylene and ECCE not only the corresponding biphenyl derivative 8 but also the linear Z and E 1:2-addition products have been isolated.