Yq. Tu et al., BROMINATION-DEHYDROBROMINATION ROUTE TO SOME NATURALLY-OCCURRING 1,6-DIOXASPIRO[4,4]-NONENES AND 1,6-DIOXASPIRO[4,4]-NONADIENES, Journal of the Chemical Society. Perkin transactions. I, (10), 1995, pp. 1309-1315
Bromination-dehydrobromination of saturated 1,6-dioxaspiro[4.4]nonanes
afforded a variety of naturally occurring 1,6-dioxaspiro[4.4]-nonenes
and -nonadienes, such as 2-5 and 8, and can be applied to give unsatu
rated spirolactones, such as 27.