Enantiomerically pure cyclopalladated diazaphospholidine

Enantiomerically pure (S)-2-(anilinomethyl)pyrrolidine (S)-2 was obtained from (S)-proline using a modified four-step procedure in a total yield of 56%. Diamine (S)-2 was converted to diazaphospholidine (S)-1 using oTolP(NMe2)2. The enantiomeric purity of ligand (S)-1 and diamine (S)-2 was determined by 31P and 1H NMR spectroscopy, respectively, using a CN-palladacycle for their chiral derivatization. Direct cyclopalladation of (S)-1, using Pd(OAc)2 in toluene under mild conditions regioselectively afforded the cyclopalladated complex with the (sp2)C–Pd bond. The aromatic C–H bond activation was confirmed by NMR spectral data and X-ray diffraction study of the PPh3 derivative of the new P∗,C∗,N∗-chiral phosphapalladacycle.

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(2R,5S)-2-(2-Methylphenyl)-3-phenyl-1,3-diaza-2-phosphabicyclo[3.3.0]octaneC18H21N2PEe = >98%[α]D24=-345 (c 1.00, CHCl3)Source of chirality: (S)-prolineAbsolute configuration: (SC)

Di-μ-chloro-bis{2-(2-methylphenyl)-3-phenyl-1,3-diaza-2-phosphabicyclo[3.3.0]octane-P,C}dipalladium(II)C36H40N4Cl2P2Pd2Ee = >98%[α]D24=-106.4 (c 0.235, CH2Cl2)Source of chirality: diastereoselective synthesisAbsolute configuration: (SCSN1SN3SP)