HOAc-Mediated Cyclocondensation of 2-Formylazaarenes and Cyclic Amines. Synthesis of Pyrrolo[1,2- a]azaarenes.

In this paper, a concise, easy-operational, high-yield, one-pot method for the synthesis of pyrrolo[1,2- a]azaarenes is described by a straightforward HOAc-mediated double condensation of substituted 2-formylazaarenes (2 equiv) and cyclic amines (1 equiv) in refluxing toluene. Only water is generated as a byproduct. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via two carbon-nitrogen (C-N) and one carbon-carbon (C-C) bond formations.

Synthesis of 2-Sulfonyl Indenes and Indanes.

In this paper, we developed facile and high-yield synthetic routes for the preparation of 2-sulfonyl indenes and indanes, including: (i) Amberlyst-15-promoted Knoevenagel reaction of ß-ketosulfones and arylaldehydes in refluxing toluene; (ii) Grignard reagent (R'MgBr) or reducing reagent (NaBH4) promoted regio- and/or stereocontrolled 1,4-addition or 1,4-/1,2-reduction of the resulting sulfonyl chalcones in THF or MeOH/THF at 25 °C; and then (iii) Amberlyst-15 mediated intramolecular Friedel-Crafts annulation of the corresponding ß-ketosulfones or ß-hydroxysulfones in toluene at reflux. This present method describes a highly efficient (3 + 2) annulation via the formation of two carbon-carbon (C-C) bonds. The DFT calculations were utilized to rationalize the regioselectivity of the addition reaction.

CuI-Mediated Synthesis of Sulfonyl Benzofuran-3-ones and Chroman-4-ones.

A concise, one-pot synthesis of sulfonyl benzofuran-3-ones and chroman-4-ones from α-sulfonyl o-hydroxyacetophenones is described, using a combination of K2CO3, CuI, and dimethylsulfoxide (DMSO). This annulation protocol generates one carbon-oxygen (C-O) bond and one carbon-carbon (C-C) bond in a highly efficient manner.