An Expedient Synthesis of Unusual Oxoisoaporphine and Annelated Quinoline Derivatives

Abstract

Several 2,3-dihydro-7H-dibenzo[de,h]quinolin-7-ones and 7H-dibenzo[de,h]quinolin-7-ones were catalytically hydrogenated over PtO 2 in acetic acid to afford 7-hydroxyquinoline and quinolone derivatives with reduced benzene rings.

New Approaches to 6‐Oxoisoaporphine and Tetrahydroisoquinoline Derivatives

“…-In agreement with the catalytic hydrogenation of 2,3-dihydro-and oxoisoaporphine derivatives [9], treatment of 6-hydroxy-5-methoxy-7H-dibenzo[de,h]quinolin-7-one (2) with PtO 2 in AcOH afforded 4 as the main product in a poor yield. Despite the use of other catalysts and solvents, such as Pd/C and toluene, respectively, the mentioned oxoisoaporphine was not generated, and the starting material was recovered.…”

“…IR Spectra: Perkin -Elmer Paragon 1000 FT-IR spectrometer at the University of Santiago de Compostela. 5-Methoxy-6H-dibenzo[de,h]quinolin-6-one (4) [9]. To a soln.…”

“…In addition, some authors reported the synthesis of 2,3-dihydro-oxoisoaporphine derivatives by cyclization of 3-{[(b-(dialkoxyaryl)ethyl]-amino}phthalides with polyphosphoric acid (PPA) [8]. Later, study of the synthesis and reactivity of these alkaloids with different substitution patterns on their isoquinoline skeleton led to several derivatives by means of metals and catalytic hydrogenation [9]. In this sense, the reactivity of some oxoisoaporphine derivatives with PtO 2 showed an unexpected keto -enol tautomerism and a later formation of the C¼O group at C(6), without evidence of a partial or complete hydrogenation of the aromatic system.…”

Complete 1H and 13C NMR spectral assignment of hydrogenated oxoisoaporphine derivatives

“…Thus, when 2,3-dihydro-7H-dibenzo[de,h]quinolin-7-one (1) 8 and 5-methoxy-2,3-dihydro-7H-dibenzo[de,h]quinolin-7-one (2) 9 were used as starting materials, they afforded in good yields 2,3,8,9,10,11-hexahydro-7H-dibenzo[de,h]quinolin-7-one (4) and 5-methoxy-2,3,8,9,10,11-hexahydro-7H-dibenzo[de,h]quinolin-7-one (5), respectively, in which only ring D is saturated. 10 However, 5-methoxy-6-hydroxy-2,3-dihydro-7H-dibenzo[de,h]quinolin-7-one (3) 9 gave the more highly reduced 1,2,3,7a,8,9,10,11,11a,11b-decahydro-7H-dibenzo[de,h]quinolin-7-one (6). 10 This difference could be attributed to the presence of the OH group at C-6 forming a hydrogen bond with the carbonyl at C-7 and affecting the reactivity of the conjugated C-7a C-11a and C-11b N bonds.…”

“…10 However, 5-methoxy-6-hydroxy-2,3-dihydro-7H-dibenzo[de,h]quinolin-7-one (3) 9 gave the more highly reduced 1,2,3,7a,8,9,10,11,11a,11b-decahydro-7H-dibenzo[de,h]quinolin-7-one (6). 10 This difference could be attributed to the presence of the OH group at C-6 forming a hydrogen bond with the carbonyl at C-7 and affecting the reactivity of the conjugated C-7a C-11a and C-11b N bonds. On the other hand, reduction of the 7H-dibenzo[de,h]quinolin-7-ones 7 and 8 afforded annelated quinolin-7-ols.…”