A rapid, convenient and chemoselective synthesis of acylals from aldehydes catalyzed by reusable nano-ordered MCM-41-SO3H

A straightforward, environmentally beneficial synthesis of spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-triones mediated by a nano-ordered reusable catalyst

A library of new spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-trione derivatives has been prepared in an efficient, one-pot pseudo four-component method mediated by a reusable heterogeneous nano-ordered mesoporous SO3H functionalized-silica (MCM-41-SO3H) catalyst. Excellent yields, short reaction times, as well as convenient non-chromatographic purification of the products and environmental benefits such as green and metal-free conditions constitute the main advantages of the developed synthetic methodology. The obtained fused indole-indenone dyes would be of interest to pharmaceutical and medicinal chemistry. Furthermore, due to their sensitivity to pH changes, they could be used as novel pH indicators.

Tungstosulfonic acid as an efficient solid acid catalyst for acylal synthesis for the protection of the aldehydic carbonyl group

Aldehydic carbonyl groups are eco-friendly protected by acetic anhydride using the tungstosulfonic acid catalyst and the deprotection is successful under the similar conditions in the presence of water.