Dyotropic rearrangement of alpha-lactone to beta-lactone: a computational study of small-ring halolactonisation

J G Buchanan, G D Ruggiero, I H Williams

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Transition structures have been optimised using the B3LYP/ 6-31+G* density functional level method, in vacuum and in implicit (PCM) and explicit (DFT/MM) aqueous solvation, for the degenerate rearrangement of the alpha-lactone derived by the formal addition of Cl+ to acrylate anion and for the dyotropic rearrangement of this to the beta-lactone. Despite being lower in energy than the alpha-lactone, there is no direct pathway to the beta-lactone from the acrylate chloronium zwitterion, which is the transition structure for the degenerate rearrangement. This may be rationalised by consideration of the unfavorable angle of attack by the carboxylate nucleophile on the beta-position; attack on the alpha-position involves a less unfavorable angle. Formation of the beta-lactone may occur by means of a dyotropic rearrangement of the alpha-lactone. This involves a high energy barrier for the acrylate derived alpha-lactone, ;but dyotropic rearrangement of the beta,beta-dimethyl substituted alpha-lactone to the corresponding beta-lactone involves a much lower barrier, estimated at about 46 kJ mol(-1) in water, and is predicted to be a facile process.
Original languageEnglish
Pages (from-to)66-72
Number of pages7
JournalOrganic and Biomolecular Chemistry
Volume6
Issue number1
DOIs
Publication statusPublished - 2008

Fingerprint Dive into the research topics of 'Dyotropic rearrangement of alpha-lactone to beta-lactone: a computational study of small-ring halolactonisation'. Together they form a unique fingerprint.

  • Cite this