Synthesis of 4H‐Benzo[e][1,3]oxazin‐4‐ones by a Carbonylation–Cyclization Domino Reaction of ortho‐Halophenols and Cyanamide

Front Cover: Synthesis of 4H‐Benzo[e][1,3]oxazin‐4‐ones by a Carbonylation–Cyclization Domino Reaction of ortho‐Halophenols and Cyanamide (ChemistryOpen 5/2017)

Silver- versus gold-catalyzed sequential oxidative cyclization of unprotected 2-alkynylanilines with oxone.

Unprecedented domino oxidative cyclization reactions of unprotected 2-alkynylanilines to give functionalized 4H-benzo[d][1,3]oxazin-4-one or benzisoxazole derivatives in moderate to good yields are achieved by silver vs. gold selective catalysis. The search for the optimal reaction conditions revealed the divergent catalytic activity of NaAuCl4·H2O and AgNO3.

Lactic acid-catalyzed Eco-friendly Cyclization Reaction for the Synthesis of 4H-benzo[b]pyrans and 3,4-dihydropyrano[c]chromenes in EtOH/H2O as an Efficient Green Reaction Medium

An environmentally friendly, green, and highly efficient process for the synthesis of biologically and pharmacologically  4H-benzo[b]pyrans  and  3,4-dihydropyrano [c] chromenes  is  developed  by condensing cyclic aromatic aldehydes, malononitrile, and dimedone or 4‐hydroxycoumarin in the presence  of  lactic  acid  as  an  efficient  and  green  catalyst.  The corresponding  products  have  b...

Uncatalyzed Synthesis of Arylmethylene[bis(5,5-dimethyl-3-hydroxy-2-cyclohexene-1-ones)] in Hot Water by Domino Knoevenagel/Michael Reactions

A simple and ecofriendly method was developed for the synthesis of arylmethylene[bis(5,5- dimethyl-3-hydroxy-2-cyclohexene-1-ones)] from the reaction of 5,5-dimethylcyclohexane- 1,3-dione and aromatic aldehydes in an aqueous media without any catalyst via Knoevenagel condensation followed by rapid Michael addition. No cyclization product was down to convert these enolic forms to xanthene deriva...

Synthesis of 4-methylene-4H-benzo[d][1,3]thiazines via a tandem reaction of 1-(2-alkynylphenyl)ketoximes with Lawesson's reagent.

1-(2-Alkynylphenyl)ketoximes react with Lawesson's reagent catalyzed by InCl(3) and cyanuric chloride leading to 4-methylene-4H-benzo[d][1,3]thiazines in good yields. This tandem reaction proceeds with high efficiency through Beckmann rearrangement, thioamide formation, and intramolecular nucleophilic cyclization.