Cyclopalladation of 1-tetralone (3,4-dihydronaphthalen-1-one) oximes
- 1 January 1981
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 1,p. 205-211
- https://doi.org/10.1039/dt9810000205
Abstract
Cyclopalladated complexes precipitate from methanolic Li2[PdCl4]–Na[O2CMe] solutions containing 1-tetralone oxime, the 6-methoxy-analogue, and the 7-substituted derivatives, substituent R = CH3–, CH3CH2–, MeO–, but reaction fails when R =(CH3)2CH–, (CH3)3C–, or –No2. The oxime derivatives of methyl 12-methoxy-7-oxopodocarpa-8,11,13-trien-19-oate and methyl 7-oxopodocarpa-8,11,13-trien-19-oate readily metallate while the oxime of methyl 7-oxoabieta-8,11,13-trien-18-oate does not. Carbonylation of the cyclopalladated 1-tetralone oxime complexes in methanol gives the corresponding 8-methoxycarbonyl-1-tetralone oximes. Hydrogen-1 n.m.r. analysis of 1-tetralone oxime and Li2[PdCl4] solutions show [PdCl2(oxime)2] is not a reaction intermediate. At –76 °C co-ordinated oxime exhibits a downfield shift for H8, characteristic of above-plane geometry of the ligand, while at O °C an upfield shift relative to the free oxime suggests in-plane geometry. The intermediate is isolable in water giving cis-[PdCl2(oxime)]·3H2O which on redissolving gives the soluble cyclometallated species [PdCl-(CN-oxime)(S)](S = solvent) and HCl by an irreversible process. Dimerisation gives [{PdCl(CN-oxime)}2] or the complex [PdCl(CN-oxime)L] in the presence of L (L = oxime or PPh3).Keywords
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