sentences:  The alkylation of the umbelliferone is initiated with the use of dimethylallyl pyrophosphate, more commonly known as DMAPP.The cyclization of an alkyl group occurs to form marmesin (4), which is done in the presence of NADPH and oxygen along with a cytochrome P450 monooxygenase catalyst.This process is then repeated twice more, first to remove the hydroxyisopropyl substituent from marmesin (4) to form psoralen (5), and then to add a hydroxyl group to form bergaptol (6).