Steric promotion in the cycloplatination of primary amines

The reactions of primary amines (S)-(−)-α-methylbenzylamine (1a) and (R)-(+)-1-(1-naphthyl)ethylamine (1b) with cis-[PtCl2(dmso)2] in the presence of Na(CH3CO2) carried out in refluxing toluene–methanol mixtures produced cyclometallated compounds [PtCl{NH2CH(CH3)C6H4}{SOMe2}] (2a) and [PtCl{NH2CH(CH3)C10H6}{SOMe2}] (2b) in moderate and quantitative yields, respectively. Compound 2b was also obtained at room temperature, in the absence of Na(CH3CO2). The reactions of 2a and 2b with phosphines were studied. The obtained compounds were fully characterized and the factors that facilitate cycloplatination of primary amines are discussed.

Cycloplatination of primary amines (S)-(−)-α-methylbenzylamine and (R)-(+)-1-(1-naphthyl)ethylamine using cis-[PtCl2(dmso)2] as precursor and standard procedures has been achieved in moderate and quantitative yields, respectively. The ease of formation of the compound derived from the bulky (R)-(+)-1-(1-naphthyl)ethylamine is evidenced from the fact that it can also be obtained at room temperature and without requiring the presence of an external base.Figure optionsDownload as PowerPoint slide