Efficient Synthesis and Structural Analysis of New Dioxopiperazine Isoquinolines

N. CABEDO, N EL AOUAD, I BERENGUER, M ZAMORA, M C. RAMIREZ DE ARELLANO, F SUVIRE, A. BERMEJO, D.ENRIZ AND D. CORTES

TETRAHEDRON

Elsevier

Lugar: Amsterdam; Año: 2006 vol. 62 p. 4408 - 4418

0040-4020

We report herein the synthesis of new dioxopiperazine isoquinolines using the Pictet–Spengler cyclisation. Our synthetic strategy for the preparation of two new compounds (5, 6), with a tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-dione moiety was developed in only four steps. To understand better the crucial step of the synthesis reported here, theoretical calculations using semiempirical (PM3), ab initio and DFT computations were carried out on a reduced system model. The structure of chlorohydrate water solvate of tetrahydro (2-piperidinylethyl)-6H-pyrazino [1,2-b]isoquinoline-1,4-dione (6$HCl$2H2O) was determined by X-ray diffraction. Theoretical calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. four steps. To understand better the crucial step of the synthesis reported here, theoretical calculations using semiempirical (PM3), ab initio and DFT computations were carried out on a reduced system model. The structure of chlorohydrate water solvate of tetrahydro (2-piperidinylethyl)-6H-pyrazino [1,2-b]isoquinoline-1,4-dione (6$HCl$2H2O) was determined by X-ray diffraction. Theoretical calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. 5, 6), with a tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-dione moiety was developed in only four steps. To understand better the crucial step of the synthesis reported here, theoretical calculations using semiempirical (PM3), ab initio and DFT computations were carried out on a reduced system model. The structure of chlorohydrate water solvate of tetrahydro (2-piperidinylethyl)-6H-pyrazino [1,2-b]isoquinoline-1,4-dione (6$HCl$2H2O) was determined by X-ray diffraction. Theoretical calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion. H-pyrazino [1,2-b]isoquinoline-1,4-dione (6$HCl$2H2O) was determined by X-ray diffraction. Theoretical calculations (RHF/3-21G and RB3LYP/6-31G(d)) were also performed for compound 6 neutralised with a chloride ion.6 neutralised with a chloride ion.