The vapor-phase reaction over activated alumina of tetrahydropyran with aniline and the toluidines has been investigated. Under optimum conditions, N-arylpiperidines were obtained in over 90% yield from aniline,m-toluidine, andp-toluidine. The cyclic ether ando-toluidine gave N-o-tolylpiperidine in a maximum yield of 66%. N-Phenylpyrrolidine was obtained in 88% yield from tetrahydrofuran and aniline as compared to 45.5% previously reported by Yur'ev.