A thermal decarbonylation of penam beta-lactams.

ABSTRACT: Penam acids 6-8 [i.e., (2S,5R,6R)-, (2S,5S,6R)-, and (2S,5R,6S)-isomers of 6-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid] were prepared by deesterification of the corresponding methyl esters 2-4. The same methodology applied to ester 1 did not lead to the (2S,5S,6S)-isomer 5 but rather a 72% yield of the thiazoline derivative 9. High-resolution mass spectrometry analysis of the reaction headspace gases indicated that a stoichiometric amount of carbon monoxide is produced during the deesterification of 1. A mechanism for this decarbonylation reaction is proposed. This appears to represent a new type of fragmentation reaction for a penam carboxylic acid. The free energies of various reaction species along viable decarbonylat

SUBMITTER: Wiitala KW 

PROVIDER: S-EPMC12311641 | biostudies-literature | 2008 Apr

REPOSITORIES: biostudies-literature