22a, R= Li; reagent=(CH,), CLi reagent= C, H, OCHO reagent= ClCOOCH, b, R= CHO; c, R= COOCH,; d, R= Br; reagent= Br, e, R= CSNHCOOC, H,; f, R= SC, H,; reagent= SCNCOOC, H, reagent= C, H, SSC, H, tetrahydrofuran removed three of the four chloro groups and furnished monochloro derivative 11 (Scheme 11). Double-resonance NMR results obtained for compound 13, the next in the sequence, served to locate the surviving chlorine on the ...