3-Chloro-2-(phenylsulfinyl)-1-propene and 3-chloro-2-(phenylsulfonyl)-1-propene: preparation and utility as reagents for .alpha.,.alpha.'-annelation of cyclic ketones
3-Chloro-2-(phenylsulfinyl)-1-propene and 3-chloro-2-(phenylsulfonyl)-1-propene: preparation and utility as reagents for .alpha.,.alpha.'-annelation of cyclic ketones