TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compounds: Metal catalyst (A) is sodium, calcium, chromium, lanthanum, cerium, tungsten, scandium, titanium, zirconium, vanadium, and/or their oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Conditions: The reduction reaction is carried out in the presence of a reaction solvent and a catalyst, preferably using metal (oxide) as catalyst and hydrogen as reducing agent, or sodium borohydride as reducing agent in the presence of nickel chloride. The reaction solvent is all polar or nonpolar solvent and the reaction temperature is -50 degrees C to 60 degrees C. The catalyst is palladium or palladium hydroxide supported on charcoal, rhodium supported on aluminum oxide, Raney nickel, or molybdenum. The molar ratio of arteannuic acid and catalyst is 1:0.01-1. The carboxyl-group protection reaction is carried out in the presence of an alkali in an organic solvent. The molar ratio of the dihydroarteannuic acid and alkali is 1:1-30 and the reaction temperature is -50 degrees C to 60 degrees C. The alkali is inorganic alkali or organic alkali. The organic solvent is used in an amount of 100-5000 mL/mol. The oxidation reaction is carried out in the presence of an alkali (organic or inorganic) and metal catalyst (A) in an organic solvent. The usage amount of solvent is 50-10000 mL/mol and the reaction temperature is -78 degrees C. The molar ratio of catalyst and compound is 1:1-100. The molar ratio of compound and peroxide is 1:1-100. The molar ratio of compound and alkali is 1:0.01-10. The rearrangement reaction is carried out in an organic solvent and oxygen atmosphere at -78 degrees C to 60 degrees C. The usage amount of solvent is 50-10000 mL/mol. The reaction is catalyzed by Bronsted acid or Lewis acid. The molar ratio of acid and compound is 1:1-100. Purification is carried out by column chromatography and recrystallization using organic or inorganic solvent. Preferred Compound: The carboxyl-group-protected compound is of formula (I).R=alkyl (preferably methyl, ethyl, propyl, isopropyl, 2-methyl-1-propyl, 2-methyl-2-propyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-butyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl-butyl, 2,2-dimethyl-1,3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl, pentyl, hexyl, heptyl, octyl, or other linear or branched hydrocarbyl), alkenyl (preferably vinyl, allyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, or 2-ethylhexenyl), alkynyl (preferably ethynyl, propynyl, butynyl, pentynyl, hexynyl, 2-pentynyl, or 5-methyl-2-heptynyl), aryl (preferably phenyl, naphthyl, anthryl, phenanthryl, biphenyl, terphenyl, triphenylmethyl, benzyl, 2-naphthylmethyl, 9-anthracenyl, 9-methylphenanthrenyl, 3-diphenylethyl, pyrrolyl, furyl, thienyl, pyridyl, benzofuranyl, benzothienyl, indolyl, quinolyl or isoquinolinyl), cycloalkyl (preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, bicycloterpenyl, cyclobutenyl, cyclopropenyl, cyclopentenyl or cyclohexenyl), formate, MOM, TMS, THP, Ac, Ms, Ts, Bz, Piv, TES, TBS, or TBDPS.