[52611-08-2]  · C26H26Cl2P2Pd  · Dichlorobis(methyldiphenylphosphine)palladium(II)  · (MW 577.75)

(catalyst for biscarbonylation of aryl halides with amines3,4)

Alternate Name: bis[(diphenylphosphino)methane]palladium(II) chloride.

Physical Data: 1H NMR (CDCl3) d 4.2 (t, CH3).

Preparative Methods: by treating commercially available K2PdCl2 (in DMF) with methyldiphenylphosphine (in CH2Cl2),1 or from K2PdCl2 (in H2O) and methyldiphenylphosphine (in CH2Cl2) using Bu4NCl (in CH2Cl2) as a phase-transfer catalyst.2

a-Keto Amides.

The title reagent (PdCl2(dppm)) is one of the most effective catalysts among transition-metal complexes for the preparation of a-keto amides and amides from aryl halides by treatment with secondary amines and carbon monoxide.3,4 These reactions are most commonly carried out without solvent at 100 °C at 10 atm of CO using a 1:3:0.1 molar ratio of aryl halide/secondary amine/PdCl2(dppm) (eq 1).

The reactivity of phenyl halides decreases in order of PhI > PhBr > PhCl,3 although the selectivity of biscarbonylation is higher with the bromo than with the iodo derivative.4 Introduction of electron-withdrawing substituents into the para position of phenyl halides enhances the reactivity but decreases the selectivity for a-keto amides.3 Amines with high basicity (pKb < 4) are essential for accomplishing the catalytic biscarbonylation. Sterically hindered amines favor formation of the a-keto amides.3

Related Reagents.

PdCl2(PBuPh2)2 has shown good results in the formation of a-keto amides from aryl halides upon treatment with secondary amines with Carbon Monoxide.3

1. Park, Y.; Kim, K.; Cho, Y. J. Korean Chem. Soc. 1992, 36, 685 (CA 1993, 118, 88 272d).
2. Lin, I. J.; Liaw, M. D. S. J. Chin. Chem. Soc. 1993, 40, 451.
3. Ozawa, F.; Soyama, H.; Yanagihara, H.; Aoyama, I.; Takino, H.; Izawa, K.; Yamamoto, T.; Yamamoto, A. JACS 1985, 107, 3235.
4. Ozawa, F.; Soyama, H.; Yamamoto, T.; Yamamoto, A. TL 1982, 23, 3383.

Janak K. Padia

Parke-Davis Pharmaceutical Research, Ann Arbor, MI, USA

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