Mercuric ion‐catalyzed hydration of derivatives of 1,4‐dichloro‐2‐butyne. Hydration of 1‐aryloxy‐4‐arylthio‐2‐butynes, 1,4‐ bis (arylthio)‐2‐butynes, and 1,4‐ bis (arylsulfonyl)‐1‐butynes

The mercuric ion‐catalyzed hydration of 1,4‐ bis (arylthio)‐2‐butynes and 1‐aryloxy‐4‐arylthio‐2‐butynes was studied. The 1,4‐ bis (arylsulfonyl)‐2‐butynes afforded 1,4‐ bis (arylsulfonyl)‐2‐butanones (7). The 1,4‐ bis (arylthio)‐2‐butynes afforded a variety of products in acetic acid among which were: 1,4‐ bis (arylthiomethyl)vinyl acetate ( 18 ); 1,4‐ bis (arylthio)‐2‐butanone ( 15 ); 1‐(arylthio)‐3‐buten‐2‐one ( 16 ); and 1‐(arylthio)‐4‐acetoxy‐2‐butanone ( 17 ). Ketone 15 eliminates arylthiol in an acidic medium yielding 16 which undergoes Michael addition of solvent to give 17. Treatment of 7 with base in the presence of a nucleophile (ArSH) analogously leads to elimination of arylsulfinic acid, followed by Michael addition of arylthiol. Hydration of 5 in methanol cleanly gave 1‐(arylthio)‐4‐methoxy‐2‐butanones ( 19 ). In contrast, 1‐aryloxy‐4‐arylthio‐24)utynes afforded chromenes ( 8 ) by intramolecular cyclization. No thiochromenes were formed in any of the examples investigated.