Saturated heterocycles, 162 [1]. synthesis and steric structures of 3,4‐disubstituted 1,6,7,11b‐tetrahydropyrimido[6,1‐a]isoquinolin‐2‐ones

Abstract

The reaction of 1‐(hydrazidomethyl)‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline 3 with aromatic aldehydes yield hydrazones 4a,b or pyrimido[6,1‐a]isoquinolines 5a‐c depending upon the proportions of the reagents. With ketones, 3 gives only hydrazones 4a‐d and 7, which can be transformed to pyrimidoisoquinolines 10a‐e and 11 with aldehydes. The ring closures are stereospecific; the relative configurations were determined by DNOE measurements.

Fused‐Skeleton Saturated Six‐Membered 1,3‐N,O, N,N and N,S Heterocycles. Fused‐Skeleton Aryl‐Substituted Saturated Isoindolones

“…In contrast, in the case of the cyclopentanefused six-membered 1,3-heterocycles, the cis isomers (46) are much more stable than the transfused counterparts (47). This is not at all obvious, because the Gibbs standard free energy difference between the analogous carbocycles, the cis-and trans-hydrindanes (48) and (49), is merely 1.3 kJ mol-l in favour of the trans isomer. (99) The corresponding value for the cisand transdecalins (50) and (51) is -10 kJ mol-l, and the trans-decalin (51) is energetically more favoured.…”

“…This is not at all obvious, because the Gibbs standard free energy difference between the analogous carbocycles, the cis-and trans-hydrindanes (48) and (49), is merely 1.3 kJ mol-l in favour of the trans isomer. (99) The corresponding value for the cisand transdecalins (50) and (51) is -10 kJ mol-l, and the trans-decalin (51) is energetically more favoured. In the case of 1,2-disubstituted 1,3-difunctionaI cyclohexane derivatives, both the cis and trans isomers (53,54) can easily be transformed to the corresponding cyclohexane-fused six-membered 1,3-heterocycles (56,57).…”

Synthesis of novel functionalized dihydroimidazo[2,1-a]isoquinolines and dihydroimidazo[2,1-a] quinolines: single crystal X-ray studies of (Z)-methyl 2-(1-(benzo[d]thiazol-2-yl)-2-oxo-1,2-dihydroimidazo[2,1-a]isoquinolin-3(10bH)-ylidene)acetate

“…[1][2][3][4][5][6][7][8][9][10] A broad range of biological activities has been reported for compounds containing the imidazolone ring that appears in many natural products, 11 which possess interesting biological activities. 12 They are inhibitors of V-RAF murine sarcoma viral oncogene homologue B1.…”

Synthesis of Some Novel 11b-Substituted Pyrimido[6,1-a]-isoquinoline Derivatives

“…This makes the pyrimido[6,1-a]-isoquinoline skeleton an important synthetic target and a lot of research has been directed towards it. Compounds of this type are usually synthesized by ring closure of suitable tetrahydroisoquinolines [1,3,[5][6][7][8][9][10][11], Bischler-Napieralsky cyclization of 1-(3,4-dimethoxyphenylethyl)barbituric acid [2] or other appropriate N-phenethyl amides [12,13]. Cyclizations of pyrimidine intermediates via N-acyliminium ions are also known [14,15].…”