Synthesis of Bi(cyclopropane) β-Amino Tricarboxylic Acids from Fulvalene

The synthesis of cyclopropane amino acids is an important process due to the occurrence ofthis moiety in natural products [1]and in several bioactive unnatural analogues [2]. Hereby wereport synthesis of bi(cyclopropane) β-amino tricarboxylic acid 6 via cyclopropanation [3] offulvalene 1 [4]followed by ozonolysis of the C-C double bond of bi(cyclopropanated)cycloadduct 3 to give tricyclic ketone 4 in high yield. This ketone 4 undergoes a Beckmannrearrangement to give rise to δ-valreolactam 5 which yields bi(cyclopropane) β-aminotricarboxylic acid 6 via hydrolysis of the amide and ester bonds. Stereoselective synthesis ofthe bi(cyclopropane) β-amino tricarboxylic acid 6 using enantiomerically pure bisoxazolineligand 7 is being investigated in our research group.