On the reaction of 2-[(4-cyano-5,6,7,8-tetrahydroisoquinolin-3-yl)oxy]acetamides with bases: 1-amino-6,7,8,9-tetrahydrofuro[2,3-c]isoquinoline-2-carboxamides and 3-amino-4-cyano-5,6,7,8-tetrahydroisoquinolines via a Smiles-type rearrangement

摘要

The treatment of 2-[(1-alkyl(aryl)-4-cyano-5,6,7,8-tetrahydroisoquinolin-3-yl)oxy]acetamides (5) with sodium ethoxide to induce a cyclization to form 5-alkyl(aryl)-1-amino-6,7,8,9-tetrahydrofuro[2,3-c]isoquinoline-2-carboxamides 4 furnished unexpected results. Compounds 5 gave rise to two different processes: the expected formation of compounds 4 and the unexpected formation of 1-alkyl(aryl)-3-amino-4-cyano-5,6,7,8-tetrahydroisoquinolines 6 (via a Smiles-like rearrangement). The characteristics of this rearrangement have been thoroughly investigated as a function of the structure of the starting 5. Moreover, by exploiting this rearrangement, 2-(5,6,7,8-tetrahydroisoquinolin-3-yl)oxy]acetohydrazides 7 gave new pyrazolo[3,4-b]pyridines 8. Thus, this rearrangement represents a new method for the synthesis of 6 and 8, compounds interesting from a biological point of view. All of the examined reactions occur with good-excellent yields, ranging between 78 and 88%. (C) 2015 Elsevier Ltd. All rights reserved.