Silica Sulfuric Acid and Al(HSO₄)₃: As Efficient Catalysts for the Formylation of Alcohols by Using Ethyl Formate under Heterogeneous Conditions

Abstract

A mixture of ethyl formate and a catalytic amount of silica sulfuric acid or Al(HSO4)3 as suitable formylating systems can formylate various alcohols to their corresponding formate ester derivatives under mild, nearly neutral and heterogeneous conditions at room temperature with good to excellent yields.

Synthesis and Crystal Structure Determination of [H2‐cryptand 222](Br3)2: A Unique Tribromide Catalyst for the Catalytic Chemoselective N‐Boc Protection of Amines

“…In continuation of our studies on the host-guest chemistry of crown ethers, [36][37][38] the synthesis and application of tribromide reagents 24,39 and the protection of organic functional groups, [40][41][42][43][44] we found that addition of Br 2 to cryptand 222 in ethanol as solvent gave the unique tribromide reagent [H 2 -cryptand 222](Br 3 ) 2 (I) which was isolated as red crystals following recrystallization from acetonitrile, (Scheme I).…”

Silica-bonded N-propyl sulfamic acid as an efficient catalyst for the formylation and acetylation of alcohols and amines under heterogeneous conditions

“…Phenols were also, acetylated in short reaction times with acetic anhydride in the presence of SBNPSA (Table 3, entries [14][15][16][17]. It is important to note that according to the previous report 39 most of these acylation reactions proceeded at 62-80°C in the presence of sulfamic acid.…”

[PVP‐SO3H] HSO4: An Efficient Polymeric Solid Acid Catalyst for the Formylation and N‐Boc Protection Reactions

“…Also, formamides employed as the major protecting groups of amines in peptide synthesis because the deprotection process can selectively take place in the presence of acetate or other ester protective groups . There are different methods for the protection of amines and alcohols in the form of formylation in the presence of various catalysts such as TiO 2 ‐P 25 , γ‐Fe 2 O 3 @HAp‐SO 3 H, HCOONa, CO 2 and Ph 2 SiH 2 , CO 2 /PhSiH 3 /TBAF, Silica sulfuric acid, HClO 4 –SiO 2 , Al (HSO 4 ) 3 and Silphos [PCl 3 ‐nSiO 2 ) n ] …”