A novel application of a [3+2] cycloaddition reaction for the synthesis of the piperazinone rings of pseudotheonamides A 1 and A 2

Catalyst-free aziridination and unexpected homologation of aziridines from imines

“…Methylation of the hydroxylic aromatic group was subsequently achieved using K 2 CO 3 /(MeO) 2 SO 2 . After Boc removal, 21 the reduction with LiAlH 4 lead to the 1,2-amino alcohol. The final step of cyclization to the aziridine ring was carried out by tosyl chloride and potassium carbonate 22 and compound 3k was obtained in 30% overall yield.…”

Mastering chiral substituted 2-oxopiperazines

“…During their studies toward the synthesis of pseudotheonamides A 1 and A 2 , Gurjar et al 13 developed a novel approach for the construction of the 3,5,6-trisubstituted piperazinone ring system of the natural products using an intramolecular [3+2] cycloaddition reaction between an azide and an a,b-unsaturated ester. The azido ester 259 was the key intermediate in this approach summarized in Scheme 49.…”

Novel and convenient to substituted imidazoles

“…More recently, great attention has been given to dipolar cycloaddition chemistry using azides, especially azide cycloadditions to alkynes to generate triazoles [5] (Scheme ). Addition of azides to α,β‐unsaturated carbonyl compounds IV has been reported in the literature [6–10] (Scheme ). Particularly interesting were the transformations of 2‐amido‐3‐arylaminoacrylates V and VII to imidazoles VI and VIII , respectively [11] (Scheme ).…”