O. K. Onajole et al.
N-Benzyl ethanolamine PCU 2
was cooled, filtered and concentrated in vacuo. The crude residue
was purified via column chromatography on silica gel using
CH3Cl : MeOH : NH4OH (88 : 10 : 2, Rf = 0.65) as eluents to give
N-benzyl homopiperazine PCU 5 as a yellow oil (0.84 g, 85%).
IR νmax: 2935, 2811, 1452, 1351, 1111, 729 and 695 cm−1. HRMS
calculated for C39H52N4O (M + H+) 593.4219, found 593.4230.
A mixture of N-ethanolamine 10 (1.2 g, 20 mmol) and benzalde-
hyde 11 (2.1 g, 20 mmol) in 20 ml of methanol was stirred at 25 ◦C
under dinitrogen atmosphere for 2 h. The mixture was cooled to 0◦
using an external ice-salt bath after which NaBH4 (1.5 g, 40 mmol)
was added slowly. The mixture was stirred overnight at RT. Excess
NaBH4 was quenched by adding 20 ml of 10% HCl, the mixture was
basified with 25% NH4OH and the product was extracted from the
mixture with DCM (2 × 30 ml). The solvent was dried over Na2SO4
and concentrated in vacuo to afford pure N-benzyl ethanolamine
13 (2.2 g, 72%). 1H NMR [CDCl3, 400 MHz]: δH 2.71 (t, 2H), 3.04 (NH),
3.60 (t, 2H), 3.75 (s, 2H), 7.23–7.33 (m, 5H). 13C NMR (CDCl3): δC:
50.6 (t), 53.4 (t), 60.6 (t), 127.0 (d), 128.1 (d), 128.3 (d), 139.6 (s).
A mixture of N-benzyl ethanolamine 13 (1.2 g, 7.9 mmol), PCU
ditosylate 8 (2 g, 3.6 mmol) and K2CO3 (0.745 g, 5.4 mmol) in
CH3CN was refluxed under nitrogen for 4 days. The reaction was
monitored on TLC, after completion the reaction was filtered
and concentrated in vacuo. The crude product was purified via
column chromatography on silica gel using CH3Cl : MeOH : NH4OH
(88 : 10 : 2, Rf = 0.7) as eluent to give N-benzyl ethanolamine PCU
2 (1.3 g, 70%). IR νmax: 3371, 2951, 1601, 1452, 1043, 732 and
697 cm−1. HRMS calculated for C33H42N2O3 (M + H+) 515.3274,
found 515.3288.
Acknowledgements
The authors thank the National Research Foundation, Gun
2046819, Aspen Pharmacare and the University of KwaZulu-Natal
for financial support.
Supporting information
Supporting information may be found in the online version of this
article.
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N-Benzyl homopiperazine PCU 5
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A mixture of N-benzyl homopiperazine and PCU ditosylate 8
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wasrefluxedfor4 daysunderN2 atmosphere. Thereactionmixture
c
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Magn. Reson. Chem. 2008, 46, 1007–1014