Palladium-assisted formation of carbon-carbon bonds Part 2.” Stoichiometric synthesis of spirocyclic compounds. X-ray structure of a wallylic palladium intermediate

Abstract

Stoichiometric reactions of arylpalladium compounds with alkynes give spirocyclic organic and organometallic compounds. The compound bis{r?-C-O-(2,3,4-trimethoxy-6-acetylphenyl)} di(p-chloro)dipalladium(II) reacts with diphenylacetylene or ethyl 3-phenylpropiolate giving 6-ace@-1,2,3,4- tetraphenyl-9,10-dimethoxy-spiro[4.5]1,3,6,9-decatetraen-8- one and 6-acetyl-1,3-dicarboxyethyl-2,4-diphenyl-9,lO-dimethoxy- spiro[4,5]1,3,6,9-decatetraen-8-one, respectively. A rrallylpalladium complex, 7~~-{6-acetyl-1,2,3,4_tetraphenyl- 8,9,lO-trimetho~-spiro[4,5]1,3,9-decatrien-6-enyl}(2,2’-bipyridine) palladium(II) trifluoromethylsulfonate solvated, with one molecule of 1,2-dichloroethane, has also been isolated and its structure determined by X-ray diffraction studies.