A general atom-economical approach for the synthesis of α-acyloxy methyl ketone is demonstrated through regioselective hydration of a wide range of propargyl acetates. Readily available catalyst comprising of 1% Ph(3)PAuCl and 1% AgSbF(6) in dioxane-H(2)O efficiently hydrolyzes the terminal alkynes of the propargyl acetate in the absence of acid promoters at ambient temperature within a short time. Effective regioselective hydration is facilitated by the neighboring carbonyl group as demonstrated through (18)O-labeling study. Compatibility of functional moieties and tolerance to various acid-labile protecting groups are observed. The catalytic condition is also suitable to perform hydration of TMS-substituted propargyl acetates, even though it requires prolonged reaction time for completion. Stereointegrity of the propargylic acetate is preserved during the hydration. The robustness of the system is successfully demonstrated through gram scale preparation of the product in nearly quantitative yield. The common α-acyloxy methyl ketone is transformed to 1,2-diol and 1,2-amino alcohol derivatives. Synthesis of actinopolymorphol B is achieved for the first time involving hydration of the propargyl acetate as the key step.

Regioselective hydration of the terminal halo-substituted propargyl carboxylate by gold(I) catalyst is reported. The mild catalytic conditions tolerate common acid-labile protecting groups, and a wide variety of α-acyloxy α′-halo ketones are efficiently synthesized within a short reaction time. The α-acyloxy α′-halo ketones are used for the synthesis of 2-aminothiazoles.

A base promoted reaction between N-protected propargyl amines and 3-bromopropiolate readily provides an array of novel stable alkyne-tethered ketene N,N-acetals in good yields. A wide range of structurally complex cyclobutene-fused azepine heterocycles are synthesized through the gold-catalyzed intramolecular cycloisomerization of ketene N,N-acetals for the first time. A plausible reaction pathway is deduced on the basis of the (1)H NMR studies.

Metal free α-halogenation of ynamides at room temperature.

Hydrate your chemistry! Hydrative cyclization of 5‐yne‐ynamides in the presence of Echavarren's catalyst and p‐toluenesulphonic acid (PTSA)⋅H2O at room temperature affords an array of 1,6‐dihydropyridin‐2(3H)one derivatives. Isomerization, epoxidation, and hydrogenation of the double bond and insertion of an extended π‐conjugate system into the pyridinone skeleton have been successfully accomplished (see scheme; Ts=tosyl).