Photochemical process for producing artemisinin

A process for preparing artemisinin, comprising the steps of:

• preparing a mixture comprising (i) a dihydroartemisinic acid derivative of formula (I)
• wherein
• X is O
• Y is formula (II)
• R1 is hydrogen;
• a C1-C12 alkyl group which is linear or branched or a C3-C10 cycloalkyl group, said alkyl group being unsubstituted or substituted by one or more substituent(s) selected from a C1-C6 alkyl group and a halogen;
• a trifluoromethyl group;
• a cycloalkylalkyl group where cycloalkyl and alkyl are as defined above;
• a C2-C12 alkenyl group which is linear or branched, said alkenyl group being unsubstituted or substituted by one or more substituent(s) selected from a C1-C6 alkyl group and a halogen;
• a C5-C14 aryl or heteroaryl group, said aryl or heteroaryl group being unsubstituted or substituted by one or more substituent(s) selected from a C1-C6 alkyl group and a halogen;
• an arylalkyl group where aryl and alkyl are as defined above;
• or a heteroarylalkyl group where heteroaryl and alkyl are as defined above;
• R3 is OR1 where R1 is as defined above;
• (ii) at least one organic solvent and (iii) a photosensitizer,
• subjecting said mixture to photooxidation by means of a light source, and
• recovering the artemisinin thus obtained.