Synthesis of Isoquinolines. III. A New Synthesis of 1,2,3,4-Tetrahydroisoquinolines¹

The Synthesis of (±)-Ochrobirine. A New Route to the Spirobenzylisoquinoline System

“…Following the procedure of Bobbitt et al (32,33) the cyclization of 3 in 6 M aqueous ethanolic HCI was attempted. Instead of the expected spiroisoquinoline we obtained the dione, 1, formed by cleavage of the C2-N bond ; glyoxal, as its bis-2,4-dinitrophenyl hydrazone was also isolated.…”

Synthesis of indeno[1,2,3-ij]isoquinolines

“…Et20/(CF3C0)20 (17) with a singular lack of success. The same was true when 11 was treated with 6 M HCI (18) or its tosyl derivative with 6 M HCI in dioxane (19). The reasons for the failure of this cyclization in this seemingly highly activated system are not apparent.…”

A New Modification of the Pomeranz-Fritsch Reaction

“…Depending on alkoxy group position cyclization rate is reduced and intermolecular reactions, solvolysis or ether deprotection begin to occur. Some modifications of the original procedure were introduced in the past by Bobbit 1 and Jackson 2 but, although they improved the yield for most of substrates, these variants still show dependence on pattern substitution.…”