New route for synthesis of 2-(2,2-dimethoxyethyl)-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole and DFT investigation

Development of efficient sequences for the synthesis of the title compound (2-(2,2-dimethoxyethyl)-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole) (7) was described. The title compound was synthesized through several steps starting from phenylhydrazine hydrochloride and dimethyl (R)-2-(3-oxocyclohexyl)malonate. In this route, all synthesized compounds were observed by spectroscopic tools (FT-IR, NMR): Methyl-2-(2,3,4,9-1H-carbazol-2-yl)acetate (3), 2-(2,3,4,9-tetrahydro-1H-carbazol-2-yl)acetic acid (4), N-(2,2-dimethoxyethyl)-2-(2,3,4,9-tetrahydro-1H-carbazol-2-yl)acetamide (5), 2-(2,2-dimethoxyethyl)-1,2,4,5,6,7-hexahydro-3H-1,5-methanoazocino[4,3-b]indol-3-one (6), 2-(2,2-dimethoxyethyl)-2,3,4,5,6,7-hexahydro-1H-1,5-methanoazocino[4,3-b]indole (7). The central step in these syntheses is the dehydrogenative reaction, which constructs the tetracyclic ring system from a much simpler tetracyclic precursor. The six-stable conformers of the compound (7) were used for further calculations such as FT-IR, NMR, NLO, and FMO analyses, performed at the B3LYP/6-311++G(d,p) level. This work revealed that (7) can be a good material to use in the non-linear optical material because its β tensor is greater ten times than that of the urea.