Synthesis of 2-Methoxy-3H-Azepine Derived Compounds Through the Thermal Reaction between Alkylnitrobenzene and Tributylphosphine

Siti Mariyah Ulfa (Jurusan Kimia Fakultas MIPA Universitas Brawijaya Malang)
Hideki Okamoto (Divisi Kimia dan Biokimia Program Pascasarjana Ilmu Pengetahuan Alam dan Teknologi Universitas Okayama 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Jepang)
Kyosuke Satake (Divisi Kimia dan Biokimia Program Pascasarjana Ilmu Pengetahuan Alam dan Teknologi Universitas Okayama 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Jepang)

Natural B
Vol 3, No 1 (2015)

Although photolysis of phenyazide has been widely reported to give 3H-azepine, the thermal deoxygenation reaction of alkylnitrobenzene derived similar products hitherto unexplored. Novel synthesis of 2-methoxy-3H-azepine derivatives was carried out using alkylnitrobenzene with tributylphosphine (Bu3P) reacted at 150°C for 24 hours in the presence of methanol. Reaction of m-nitrobenzene with the above methods gave two isomers of 3H-azepine, namely, 2-methoxy-6-methyl-3H-azepine and 2-methoxy-4-methyl-3H-azepine in 61%. Reaction of 2,3-dimethylnitrobenzene with Bu3P afforded the three isomers, that is, 2-methoxy-6,7-dimethyl-3H-azepine; 2-methoxy-3,4-dimethyl-3H-azepine and 7-methoxy-5,6-dimethyl-4H-azepine. Reaction of 3,5-dimethylnitrobenzene gave the sole product of 2-methoxy-4,6-dimethyl-3H-azepine in 42%. In contrast, reaction of 2,6-dimethylnitrobenzene didn’t give any product because the steric effect of methyl groups attached on C2 and C6. Structure elucidation of all novel products have confirmed by HETCOR.