91686-91-8Relevant academic research and scientific papers
A menschutkin type amine alkylation involving methyl transfer to benzylamine from palladium(II) chelate complexes of o-(diphenylphosphino)thioanisole
Benefiel, Annamarie,Max Roundhill,Fultz, William C.,Rheingold, Arnold L.
, p. 3316 - 3324 (2008/10/08)
The reactions between the complexes PdCl2(o-Ph2PC6H4SMe) and [Pd(o-Ph2PC6H4SMe)2](BF 4)2 and benzylamine yield the respective thiolato compounds [PdCl(μ-SC6H4PPh2-o)]2 and Pd(o-Ph2PC6H4S)2. The other product is N-methyl-benzylamine. Conductivity measurements on acetonitrile solutions of PdCl2(o-Ph2PC6H4SMe) show partial substitution of chloride by benzylamine to give [PdCl(PhCH2NH2)(o-Ph2PC6H 4SMe)]Cl. Time-dependent intensity measurements on the decrease in the 1H NMR resonance of the methyl group of the palladium(II) complexes give a rate law: rate = k2[Pd complex][PhCH2NH2]. Respective rate constants for PdCl2(o-Ph2PC6H4SMe) and [Pd(o-Ph2PC6H4SMe)2](BF 4)2 are in the 10-5 and 10-3 mol-1 s-1 range. The complex [Pd(o-Ph2PC6H4SMe)2](BF 4)2 has cis stereochemistry (4J(PH) = 4 Hz), and the partially demethylated intermediate [Pd(o-Ph2PC6H4SMe)(o-Ph2PC 6H4S)]BF4 also has cis stereochemistry (4J(PH) = 3.6 Hz). The final complex Pd(o-Ph2PC6H4S)2 has trans stereochemistry, which is confirmed by X-ray crystallography. The complex PdS2P2C36H28 has a = 9.735 (3) A?, b = 12.865 (3) A?, and c = 12.732 (4) A? and crystallizes in the monoclinic P21/c space group with Z = 2. The activation parameters for the methylation of benzylamine in acetonitrile solvent are ΔH? = 12 (2) kcal mol-1 and ΔS? = -41 (10) cal K-1 mol-1. A mechanism is proposed for these reactions whereby the amine undergoes nucleophilic attack by an SN2 Menschutkin type reaction at the methyl group of the coordinated thioether. The complex PtCl2(o-Ph2PC6H4SMe) has been prepared, and the complex NiCl2(o-Ph2PC6H4SMe) also was found to methylate benzylamine.
