PEG–SO3H as an efficient and reusable catalyst for chemoselective synthesis of 1,1-diacetates

Synthesis of α-Formylated N-Heterocycles and Their 1,1-Diacetates from Inactivated Cyclic Amines Involving an Oxidative Ring Contraction

A novel synthesis of pyrrolidine-2-carbaldehydes or tetrahydropyridine-2-carbaldehydes from the cascade reactions of N-arylpiperidines or N-arylazepanes is presented. Mechanistically, the formation of the title compounds involves an unprecedented oxidative ring contraction of inactivated cyclic amines via Cu(OAc)₂/KI/O₂-promoted oxidative cleavage and reformation of the C-N bond. Interestingly, when PhI(OAc)₂ was used in place of KI, 1,1-diacetates of the corresponding aldehydes were directly obtained with good efficiency. To the best of our knowledge, this is the first example of regioselective C(sp³)-H bond functionalization and C(sp³)-N bond activation of saturated cyclic amines using copper salt and oxygen.

Sulfonated polyethylene glycol (PEG-OSO3H) as a polymer supported biodegradable and recyclable catalyst in green organic synthesis: recent advances

The objective of this review is to summarize some of the recent advances in a sulfuric acid-modified polyethylene glycol 6000 (PEG-OSO₃H) as a stable, recyclable and bio-degradable polymeric catalyst in green organic synthesis.