Rearrangement of 2,2′-spirobichroman derivatives having electron donating substituents into 4,4′-dihydroxy-1,1′-spirobiindane analogues was effected by boiling solution of the former in HBr- or HI-HBr-acetic acid.
                                    前者在 HBr- 或 HI-HBr- 
乙酸中的沸腾溶液可将具有电子捐赠取代基的 2,2′-spirobichroman 衍
生物重排为 4,4′-dihydroxy-1,1′-spirobiindane 类似物。