Pyrolysis of N-formylacetamides. Imide-isoimide rearrangement

Reaction of Carboxylic Acids and Isonitriles in Small Spaces

“…The pathway undoubtedly involves the intermediate O -acyl isoamide (the acyclic version of an azlactone) followed by the Mumm rearrangement of the acyl from O to N. To our knowledge, no observations of this intermediate from isonitriles and acids are consistent with spectroscopic data, but the analogous intermediate from substituted nitrilium ions and carboxylates is known and can be intercepted with external nucleophiles such as amines to give amides or react with another molecule of carboxylic acid to give a symmetric anhydride. The overall reaction of Scheme is known to be reversible at high temperatures…”

“…Second, the capsule arranges the acid and isonitrile in the appropriate orientation. The long butyl group of the isonitrile pushes the reactive centers toward the middle of the capsule where the seam of hydrogen bond donor and acceptor can stabilize polar transition states . The acyl rearrangement involves a four-membered ring which creates a great deal of strain, but the n -butyl group is apparently flexible enough to accommodate the necessary motions inside.…”

Synthesis of Acrylonitrile from Renewable Lactic Acid

“…[34] Elimination of acetic acid from the acetylated amide proceeds intramolecularly via the four-membered rings 4 and 5.T hese transition states are assumptions, but similar structures were discussed by Hoy and Poziomek. [35] Depending on which heterocyclic transition state is formed, either 3 leading to ACN or 6 are the next intermediates. Intermediate 6 can decompose at 500 8Ct oa cetaldehydea nd CO as reported by Golomb and Ritchie.…”

Rearrangement reactions involving the cyano group

“…The thermal rearrangement of isonitriles to nitriles (equation 1) was recognizcd a century ago by Gautier" and has been infrcqucntly examined since that time7b-h, but received more attention during 16. Rearrangement Reactions Involving the Cyano Group aa7 (1) the last decade.…”

“…Moreover, there has recently appeared what may be the first case of the reverse reaction, namely, a nitrile to isonitrile transformatior6 Talat-Erbin25 reported that under gamma irradiation such a transformation occurred. Although the cyanides of silver, copper and mercury undergo displacement reactions with alkyl halides to produce isocyanides'' (equation 16) …”