8-(2-(1,3-Dioxolan-2-yl)ethyl)-1,4-dioxaspiro[4.5]dec-6-en-8-yl phenyl sulfone 8-(2-(1,3-Dioxolan-2-yl)ethyl)-8-(phenylsulfonyl)-1,4-dioxaspiro[4.5]dec-6-ene AIDS-141957 AIDS141957 NSC658460