Abstract: The present invention relates to a method for preparing the pyripyropene compound of the formula (I) which method comprises the following steps: i) subjecting a pyripyropene compound of formula Pyripyropene A to an alkaline hydrolysis to yield a 1,7,11-trideacetylpyripyropene A, ii) reacting 1,7,11-trideacetylpyripyropene A obtained in step i) with cyclopropane carbonyl chloride to yield a raw product containing the pyripyropene compound of formula (I); iii) subjecting the raw product of step ii) to crystallization to yield a crystalline pyripyropene compound of formula (I) and a mother liquor; and iv) recycling the mother liquor or a pyripyropene compound containing fraction thereof to the alkaline hydrolysis of step i).

Abstract: The invention pertains to processes to produce dry biomass of pyripyropene producer organisms, processes to obtain pyripyropenes from such dry biomass, as well as to processes to produce compounds of Formula III and/or Formula IV and/or Formula V from the pyripyropenes obtained from the dry biomass. The invention does further pertain to the dry biomass itself, as well as processes using said dry biomass to obtain pyripyropenes for the production of compounds of Formula III and/or Formula IV and/or Formula V, including processes using said dry biomass to obtain pyripyropenes or compounds of Formula III and/or Formula IV and/or Formula V in order to produce pest control compositions, in particular insecticides, comprising such compounds.