Cinnamic acid: synthesis of the latest generation of angiotensin-converting enzyme inhibitors ACEI by inhibiting the AngII generation so that the vein dilation, peripheral resistance decreased, the mean arterial pressure, diastolic and systolic blood pressure decreased. It applies to the period of high blood pressure, is commonly used antihypertensive drugs, is one of the best antihypertensive drugs. Since its inception in the 1970s, angiotensin-converting enzyme inhibitors have been developed to the second generation. Captopril is the first generation, second generation non-thiol angiotensin-converting enzyme inhibitors, such as enalapril, benazepril, in La Puli, lisinopril, perindopril, etc. Recently, some studies have found that the use of Cinnamic acid as raw materials to the latest generation of synthetic series of angiotensin-converting enzyme inhibitors Plymouth drug intermediate 2 - oxo-4 - phenyl butyric acid (OPBA). The synthesis process is：Cinnamic acid, acrylic acid hydrogenation to be, obtained after ester of acrylic acid ethyl ester, and then to acrylic acid ethyl ester by condensation with diethyl oxalate reaction of intermediate 3 - benzyl-2 - oxo-succinic malonate, and then by dilute sulfuric acid hydrolysis OPBA. Orthogonal experiment on the synthesis of the key steps OPBA ethyl styrene condensation with diethyl oxalate - a comprehensive optimization of the hydrolysis reaction, to be suitable conditions for the synthesis of n (styrene-acrylic acid ethyl ester): n (oxalic acid diethyl acetate) = 1:3; reaction temperature is 60V; condensation time is 1.5 hours; hydrolysis time of 15 hours, OPBA yield of 65%. Cinnamic acid synthesis with the latest generation of angiotensin-converting enzyme inhibitor drugs, which is characterized protect the heart, kidneys and other vital organs of the role; Retains potassium, so potassium and diuretics at the same time the application without an increase in drug or combination of potassium potassium-sparing diuretics; decline in blood pressure, maintain or increase the vital organs heart, brain, kidney perfusion.