Abstract: The present invention discloses a synthesis method of ursodeoxycholic acid by using the plant-derived compound BA as a raw material to synthesize ursodeoxycholic acid through the steps of ethylene glycol or neopentyl glycol protection, oxidation, Wittig reaction, deprotection, reduction and hydrolysis, etc. The raw materials used for the synthesis of ursodeoxycholic acid in the present invention are cheap and easy to get, the synthesis steps are easy to operate, the yield is high, the reaction is environmentally friendly, and the industrial production is convenient.

Abstract: An optical lens includes a first lens having negative power, a second lens having positive power, a third lens, a fourth lens, and a fifth lens having positive power. The third lens and the fourth lens form an achromatic lens group. The fifth lens has two surfaces and at least one of the two surfaces is an aspherical surface.

Abstract: An optical lens includes a first lens having negative power, a second lens having positive power, a third lens, a fourth lens, and a fifth lens having positive power. The third lens and the fourth lens form an achromatic lens group. The fifth lens has two surfaces and at least one of the two surfaces is an aspherical surface.