The acid promoted rearrangement of syn-1 with HCl led to bicyclic acetal 2 from which enantiopure furan derivative 4 was obtained by hydrogenolysis. The same sequence was applied to anti-1 leading to bicyclus 3 and diastereomeric tetrahydrofuran 5. Treatment of syn-6 with pyridinium hydrogen fluoride provided either semiacetal 7 or bicyclic acetal 8, depending on the ratio of HF and pyridine. Lewis