Kimiko Tanabe

Synthesis of phenethylamine moiety by photoamination of styrene derivatives with ammonia

Abstract The photoaminations of trans-1-arylpropenes and 7-methoxy-1,2-dihydronaphthalenes with ammonia in the presence of dicyanobenzene gave 1-aryl-2-propylamines and 2-amino-6-methoxy-1,2,3,4-tetrahydronaphthalenes, respectively. The yields of the aminated compounds were improved by the addition of 1,3,5-triphenylbenzene or m-terphenyl.

Photoinduced nucleophilic addition of ammonia and alkylamines to methoxy-substituted styrene derivatives

Abstract The photoaminations of trans -1-arylpropenes (aryl = 2-methoxyphenyl ( 1 ), 3-methoxyphenyl ( 2 ), 3,4-dimethoxyphenyl ( 3 ), and 4-methoxyphenyl ( 4 )) with NH 3 , i -PrNH 2 , and t -BuNH 2 (RNH2) in the presence of p -dicyanobenzene ( p -DCB) gave 2-alkylamino-1-arylpropanes ( 9 ) and/or 2-alkylamino-1-aryl-1-(4-cyanophenyl)propanes ( 10 ). The photoaminations of 1,2-dihydro-7-methoxynaphthalenes ( 6–8 ) with RNH 2 in the presence of p -DCB gave mainly 2-alkylamino-1-(4-cyanophenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalenes ( 13 ). The photoamination of trans -1-(3,5-dimethoxyphenyl)propene ( 5 ) with i -PrNH 2 occurred at aromatic ring to give trans -1-(2-isopropylamino-3,5-dimethoxyphenyl)propene ( 11 ). The photoaminations of 1–4 and 6–8 with NH 3 in the presence of m -dicyanobenzene gave the aminated products without incorporation of cyanophenyl group. Furthermore, the addition of 1,3,5-triphenylbenzene and m -terphenyl for these reactions improved the yields of the photoaminated products.

Regiochemistry on photoamination of methoxy-substituted phenanthrenes via electron transfer

Abstract Photoaminations of several methoxy-substituted phenanthrenes (ArH) with ammonia in the presence of m-dicyanobenzene (A) were investigated. The photoamination of 2-methoxyphenanthrene (1a) and 3-methoxy-phenanthrene (1b) gave 1-amino-2-methoxy-1,4-dihydrophenanthrene (2a) and 9-amino-3-methoxy-9,10-dihydrophenanthrene (2b) respectively. The photoamination of 3,6-dimethoxyphenanthrene (1c) gave 9-amino-3,6-dimethoxy-9,10-dihydrophenanthrene (2c), while no photoamination of 2,3-dimethoxyphenanthrene (1d) and 2,3,4-trimethoxyphenanthrene (1e) occurred. The photoamination proceeds via the nucleophilic addition of ammonia to the cation radicals of ArH (ArH.+) generated by the photochemical electron transfer to A. Therefore the regiochemistry on photoanimation is related to the distribution of the positive charge in ArH.+. In order to compare the reactivity of the cation radical of 9-methoxyphenanthrene (1f) with that of parent phenanthrene, the rate constant for nucleophilic addition to the cation radical of 1f was determined by kinetic analysis.

Photochemical reactions of o-alkenylphenols and 1-alkenyl-2-naphthol with alkylamines: amination via photoinduced proton transfer

Irradiation of o-alkenylphenols 1a–c and 2a–e in the presence of alkylamines gave o-(1-alkylaminoalkyl) phenols 4a–n and 5a–e in relatively good yields. Deprotonation of these o-alkenylphenols by the amines occurs in the excited singlet state to give the excited singlet state of the phenolate anion 7 and the ammonium ion. The proton transfer from the ammonium ion to the alkenyl group of 7 generates the zwitterion 8 that allows the nucleophilic addition of the amine at the benzylic cation centre. Similar photoamination of 1-(2-methylpropenyl)-2-naphthol 3 with alkylamines occurred to give 1-(1-alkylamino-2-methylpropyl)-2-naphthols 6a–b.