Richard Elmer Holmes

Asymmetric synthesis of 4-[(t-butoxycarbonyl)amino]-pyrazolidin-3-one : precursor to bicyclic pyrazolidinone antibacterials

Abstract The preparation of chiral pyrazolidin-3-one 1 is described. The key step was cyclization via a Mitsunobu reaction using the trifluoroacetyl group to activate the terminal nitrogen.

Synthesis of a 3-keto bicyclic pyrazolidinone using a Curtius rearrangement

The synthesis of bicyclic pyrazolidinone 2 is described. Traditional methods for penem and cephem ring cyclization were found to be unsuccessful and new methodology using a Curtius rearrangement was utilized. The 3-enamine 11 was hydrolysed to the desired β-keto ester 2b without substantial loss of the t-BOC protecting group.