Laboratory Synthesis Of Benazepril

Preparation of  Benazepril

IUPAC name Benazepril  [S- (R *,R *)]-3- [[1- (ethoxy carbonyl)- 3- phenyl propyl ]amino]- 2 ,3 ,4 ,5- tetra hydro- 2- oxo- 1 H- 1- benzazepine- 1- acetic acid

Benazepril Use: antihypertensive (ACE inhibitor)

Benazepril MW: 424.50

Benazepril MF: C24H28N2O5

Benazepril M.p. 148.5°.

Proprietary names. Briem; Cibace; Cibacen; Cibacene; Labopal; Lotensin; Tensanil; Zinandril.

C₂₄H₂₈N₂O₅,HCl=461.0

CAS—86541–74–4

A white to off–white crystalline powder. It is soluble in water, ethanol and methanol.

Partition Coefficient.

Log P(octanol/water), 3.50.

Gas Chromatography.

System GP—RI 3030 (benazepril-ME); RI 2985 (M (benazeprilate)-ME3).

Column: 3% OV-101 on Gaschrom Q, 80–100 mesh (Ciba-Geigy), pyrex glass (1.5 m × 2 mm i.d.). Column and injector port temperature: 275°. Carrier gas: helium, flow rate 30 mL/min. MS detection (EI, SIM). Retention times: benazepril (methyl ester derivative) 2.55 min; benazeprilat (derivative) 2.3 min. [G. Kaiser et al.,J. Chromatogr.,1987, 419, 123–133].

High Performance Liquid Chromatography.

System HAA—retention time 17.0 min.

Column: C₁₈ (RP-BDS, 5 μm packing, 250 × 3 mm i.d.). Mobile phase: sodium dihydrogen phosphate (0.025 M, pH 4.8):acetonitrile (55:45). 0.4 mL/min flow rate. UV detection (λ=250 nm). Retention time: benazepril hydrochloride, 4.95 min. [I. E. Panderi and M. Parissi-Polou,J. Pharm. Biomed. Anal.,1999, 21, 1017–1024].

Column: Hypersil ODS (5 μm, 250 × 4.5 mm). Mobile phase: sodium heptanesulfonate (20 mM, pH 2.5):acetonitrile (5% THF) (52:48 v/v), 1.0 mL/min flow rate. UV detection (λ=215 nm). Retention time: 15 min. [D. Bonazzi et al.,J. Pharm. Biomed. Anal.,1997, 16, 431–438].

Ultraviolet Spectrum.

Aqueous acid (0.2 M NH₂SO₄)—237 nm; basic—241 nm; aqueous acid (0.1 M hydrochloric acid)—237.2 nm (hydrochloride salt).

Reference(s):
Clarke's Analysis of Drugs and Poisons
Watthey, J.W.H. et al.: J. Med. Chem. (JMCMAR) 28, 1511 (1985).
US 4 410 520 (Ciba-Geigy; 18.10.1983; prior. 11.8.1981, 9.11.1981, 19.7.1982).
EP 72 352 (Ciba-Geigy; appl. 5.8.1982; USA-prior. 11.8.1981, 9.11.1981).