重氮甲烷   、                                                                                      
(+-)-4-hydroxy-3ξ-hydroxymethyl-3ξ-methyl-1-oxo-(4ar,8ac)-octahydro-4t,7t-cyclo-isochromene-8t-carboxylic acid                                                                                                                                                              在
                                                                                                                                                                                 
乙醚                                                                                                                                  作用下,
                                                                                                                                                                                                                            生成                                                 (+/-)-4-hydroxy-3ξ-hydroxymethyl-3ξ-methyl-1-oxo-(4a
r,8a
c)-octahydro-4
t,7
t-cyclo-isochromene-8
t-carboxylic acid methyl ester