Aniline → 1-Phenylpiperidine

Cyclic ethers, namely ethers in which an oxygen atom is in a ring system, are also suitable for the practice of this invention provided the ring system of the cyclic ether contains only carbon and from 1 to 3 oxygen atoms in an unstrained ring (i.e., the ring contains at least four carbon atoms and at least one oxygen atom bonded to two separate carbon atoms of the ring). Examples of such cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, tetrahydro-2-furancarbinol, 2-ethoxymethyl tetrahydrofuran, 2-butoxymethyl tetrahydrofuran, tetrahydrofuroic acid, methyl tetrahydrofuroate, tetrahydropyran, 2-methyltetrahydropyran, furan, dihydrofuran, pyran, dihydropyran, and the like. In the case of such cyclic ethers as tetrahydrofuran, tetrahydropyran and their suitably substituted congeners, reaction with primary aromatic amines such as aniline and nuclear alkylanilines (e.g., toluidines, xylidines, o-, m-, p-ethylaniline, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-diethylanilines, etc.) results in gem-dialkylation of the nitrogen atom whereby N-arylated cyclic amines are formed. In some instances, this reaction proceeds with high conversions of the aromatic amine and produces the product in very high yield. For example, reaction between tetrahydrofuran and aniline at 250° C. using a TiO2 catalyst (LHSV of 0.2 per hour) gave a 98% conversion of aniline with a 97% yield of 1-phenyl-pyrrolidine. Similarly, tetrahydropyran and aniline when reacted at 300° C. over a TiO2 catalyst (LHSV of 0.2 per hour) resulted in a 74% aniline conversion with a 98% yield of 1-phenylpiperidine.

ORD record

ord-cf7733747ab540388898f7636c170f84

Source dataset

uspto-grants-1988_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04721810