71 no 6 pp 1059 1064 1999 japanese patent application laid open no 239385 1996 japanese patent application laid open no 184158 1994 wo 2004 060065 japanese patent application laid open no 259569 1996 or bioorganic medicinal chemistry letter vol 5 no 22 p 2683 when compound a1 as a starting material is pyripyropene a pyripyropene a may be one produced by a process described in journal of synthetic organic chemistry 1998 vol 56 no 6 p 478 488 or wo 94 09147 compound b1 may also be a derivative produced by a process described for example in japanese patent application laid open no 259569 1996 or journal of technical disclosure no 50997 2008 a process described in wo 2009 022702 may be mentioned as a process for producing compound b1 from compound a1 and compound b1 may be produced by hydrolyzing acyl at the 1 position 7 position and 11 position of compound a1 in the presence of a base more specifically solvents usable herein include alcohol solvents having 1 to 4 carbon atoms such as methanol ether solvents such as diethyl ether diisopropyl ether tetrahydrofuran and dioxane aprotic polar organic solvents such as n n dimethylformamide dimethylsulfoxide n n dimethylacetamide and acetonitrile halogenated solvents such as dichloromethane and chloroform or water and mixed solvents composed.