Regioselective Arylation and Alkynylation of 2,3‐Dibromo‐1H‐inden‐1‐one by Suzuki?Miyaura and Sonogashira Cross‐Coupling Reactions

Suzuki? Miyaura reactions of 2,3‐dibromo‐1H‐inden‐1‐one afforded a wide range of arylated 1H‐inden‐1‐ones. Sonogashira cross‐coupling reactions gave alkynylated indenones. The reactions proceeded with very good regioselectivity in the less sterically hindered and more electron‐deficient position 3.     

Iron Salts in the Catalyzed Synthesis of 5‐Substituted 1H‐Tetrazoles

Clicking iron : Cheap and environmentally friendly [Fe(OAc)₂] is used for the catalysis of cycloadditions between aryl nitriles and trimethylsilyl azide to prepare substituted 1H‐tetrazoles in good yield (see scheme).

     

A Synthetic Study of Chiral α‐Hydroxy‐H‐Phosphinates Based on Proline Catalysis

A highly enantioselective synthesis of α‐hydroxyphosphinates was achieved based on the L ‐proline‐catalyzed aldol reaction of α‐acylphosphinates and acetone. Due to the preexisting chirality at the phosphorus center, mixtures of two diastereomers of the α‐hydroxyphosphinates were obtained in moderate to good yields, with simultaneously high enantioselectivity for both diastereomers. The products could be converted into α‐hydroxy‐H‐phosphinates with satisfactory yields. Furthermore, an unprecedented oxidation–reduction reaction of the α‐hydroxyphosphinates or α‐hydroxy‐H‐phosphinates to form phosphonates was observed, and the mechanism involved in such a chemical transformation is discussed.     

One‐Pot Synthesis of 4‐(2,3‐Dihydro‐2‐hydroxy‐1,3‐dioxo‐1H‐inden‐2‐yl)‐Substituted 1‐Aryl‐1H‐pyrazole‐3‐carboxylates via a Tandem Three‐Component Reaction

The hitherto unreported, highly functionalized 1H‐pyrazole‐3‐carboxylates 3 have been synthesized in good yields via a one‐pot three‐component domino reaction of phenylhydrazines, dialkyl acetylenedicarboxylates, and ninhydrin under mild conditions for the first time. No co‐catalyst or activator is required for this multicomponent reaction, and the reaction is, from an experimental point of view, simple to perform (Scheme 1). The structures of compounds 3 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization/addition reaction is proposed (Scheme 2).