Description
Naftopidil was launched in Japan for the treatment of dysuria
associated with benign prostatic hypertrophy (BPH). It can be prepared by a two
step route starting with α-naphthol. Naftopidil is a potent postsynaptic-selective
alpha-l-antagonist with a slightly higher affinity for the human prostatic than for
the aortic alpha-adrenoceptor. It also shows a 5-HT1A agonistic effect, as well
as a weak calcium antagonistic activity, but no alpha-2 or beta-adrenoreceptor
affinity. In experiments with rats or rabbits, Naftopidil was shown to be more
potent and selective for the urodynamic effect than the hypotensive effect.
Aromatic or aliphatic hydroxylation are the major routes of metabolism,
producing metabolites with a profile similar to the parent compound.
Synthesis
The general procedure for the synthesis of 1-(4-(2-methoxyphenyl)piperazin-1-yl)-3-(naphthalen-1-yloxy)propan-2-ol from 3-(1-naphthyloxy)-1,2-epoxypropane and 1-(2-methoxyphenyl)piperazine was as follows: with reference to the synthesis of Example 1 (RS)-naphthalenophenedil (HUHS1001), to a solution of 2-((1-naphthyloxy)methyl) ethylene oxide (100 mg, 0.50 mmol) to a solution of 2-(2-methoxyphenyl)piperazine (95 μL, 0.60 mmol) in ethanol (1 mL). The reaction mixture was stirred at room temperature for 1 hour. Subsequently, the reaction mixture was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to afford (RS)-naphthodil (199 mg, 100% yield). The structure of the product was confirmed by 1H-NMR (400 MHz, CDCl3) and ESI-HRMS (cation, sodium formate).1H-NMR data were as follows: δ 2.72-2.76 (m, 4H), 2.92-2.95 (m, 2H), 3.09-3.18 (m, 4H), 3.87 (s, 3H), 4.16 (dd, J = 9.6 and 5.0 Hz, 1H), 4.24 (dd, J = 9.6 and 5.0 Hz, 1H), 4.28-4.34 (m, 1H), 6.84 (d, J = 7.8 Hz, 1H), 6.87 (d, J = 7.8 Hz, 1H), 6.91-6.98 (m, 2H), 7.00-7.04 (m, 1H), 7.39 (t , J = 8.2 Hz, 1H), 7.44 (d, J = 8.2 Hz, 1H), 7.47-7.51 (m, 2H), 7.79-7.81 (m, 1H), 8.26-8.29 (m, 1H).ESI-HRMS (cation, sodium formate) Calculated value: C24H29N2O3 ([M + H]+) m/z 393.2173 , measured value 393.2148.
References
[1] Patent: US2015/353473, 2015, A1. Location in patent: Paragraph 0179-0181
[2] Patent: JP6041303, 2016, B2. Location in patent: Paragraph 0064-0066
[3] Journal of Organic Chemistry, 2007, vol. 72, # 10, p. 3713 - 3722
[4] Patent: US3997666, 1976, A
![2-[(1-Naphthyloxy)methyl]oxirane](/CAS/GIF/2461-42-9.gif)
