Facile Conversion of Aldehydes to 1,1-Diacetates Catalyzed by H-ZSM-5 and Tungstosilicic Acid

Update 1 of: Protection (and Deprotection) of Functional Groups in Organic Synthesis by Heterogeneous Catalysis

“…HZSM-5 catalyst (SAR = 180) was employed to promote the protection of different aldehydes (Table , entry 8), showing a remarkable shape selectivity; in fact, a substantial difference in the reaction rate for the ortho - and para -substituted aromatic aldehydes was observed.…”

“…243 Other functionalities, such as nitro, ether, cyano, furyl, and (Z)-double bond, were preserved, and, more importantly, since ketones were not reactive with this reagent, the method offers the advantage to perform the protection of an aldehyde functionality in the presence of a ketone (Scheme 29). HZSM-5 catalyst (SAR ) 180) was employed to promote the protection of different aldehydes (Table 24, entry 8), 244 showing a remarkable shape selectivity; in fact, a substantial difference in the reaction rate for the ortho-and parasubstituted aromatic aldehydes was observed.…”

Protection (and Deprotection) of Functional Groups in Organic Synthesis by Heterogeneous Catalysis

“…HZSM-5 catalyst (SAR ) 180) was employed to promote the protection of different aldehydes (Table 24, entry 8), 244 showing a remarkable shape selectivity; in fact, a substantial difference in the reaction rate for the ortho-and para-substituted aromatic aldehydes was observed.…”

A succinimide-N-sulfonic acid catalyst for acetylation reactions in absence of a solvent

“…[Hmim]HSO4 [43], p-toluenesulfonic acid (p-TSA) [44], silica-bonded S-sulfonic acid [45], silicasuloric acid [46], copper methanesulfonate-HOAc [47], 1,3-dibromo-5,5-dimethylhydantoin [48], ZnCl2 [49], FeCl3 [50], PCl3 [51], InCl3 [52], cyanuric chloride [53], ceric ammonium nitrate (CAN) [54], NBS [55], WCl6 [56], SbCl3 [57,58], ZrCl4 [59], LiClO4 [60], Sc(OTf)3 [61], Cu(OTf)2 [62], Bi(OTf)3 [63], LiOTf, [64], In(OTf)3 [65], montmorillonite clay [66], expansive graphite [67], H3PMo12O40 [68], H6P2W1O62•24H2O [69], AlPW12O40 [70], zirconium sulfophenyl phosphonate [71] or Bi(NO3)3•5H2O [72]. Although some of these catalysts can convert aldehydes to the corresponding diacetates with good to high yields, the majority suffer from at least one disadvantages such as prolonged reaction times, reaction under oxidizing conditions, use of a strong acid, low yields, harsh reaction conditions, difficulty in the preparation, moisture sensitivity of the reagent used, or high cost and high toxicity of the reagent used.…”