39I don't think that syn OTs will leave...anti-periplanar conformation is preferred. OH is a bad leaving group but I'd go with OH being eliminated instead of OTs here I guess...E1CB style. OTs can't be eliminated as it is syn to the abstractable(most acidic) hydrogen.
Or I may be wrong...anti conformation is mostly used in E2 type reactions. I don't know what conformation is preferred in E1CB.
