Cyclopalladated Complexes Derived from Phenylacetone Oxime. Insertion Reactions of Carbon Monoxide, Isocyanides, and Alkynes. Novel Amidines of the Isoquinoline Series

Neutral and cationic
six-membered C,N-palladacycles
with the core “Pd­{C,N-C6H4{CH2C­(Me)NOH}-2}” have been obtained by
oxidative addition of the oxime BrC6H4{CH2C­(Me)NOH}-2 to “Pd­(dba)2”
(dba = dibenzylideneacetone) in the presence of mono- or bidentate
ligands. The oximato complex [Pd­{μ-C,N,O-C6H4{CH2C­(Me)NO}-2}­(PTol3)]2 forms after dehydrobromination of the appropriate
oxime complex with KtBuO, while the pincer derivative [Pd­{C,N,N′-C6H4{CH2C­(Me)NOCH2py}-2}­Br] results by attack of an in situ generated oximato complex to BrCH2py·HBr. Insertion
of CO or RNC in some of the palladacycles causes a depalladation/coupling
process, giving 1,2-dihydro-1-oxo-2-hydroxy-3-methylisoquinoline or
1,2-dihydro-1-imino­(R)-2-hydroxy-3-methylisoquinoline, respectively,
while the insertion of alkynes produces eight-membered alkenyl­(oxime)
palladacycles “Pd­{C,N-C­(R′)C­(R)­C6H4{CH2C­(Me)NOH}-2}”.
When using diphenylacetylene, a dimeric tetranuclear complex [{Pd­(tbbpy)}2{μ-N,O-{η3-C6H4(C4Ph4)­{CH2C­(Me)NO}}}]24+ forms instead, in which a π-allyl-coordinated
oximato, bearing a spirocyclic substituent, acts as the bridging ligand.
The crystal structures of the oxime and of each type of complexes
have been determined.