The unprecedented eco-friendly Pt-catalyzed 5-endo-dig cycloisomerization of readily available a-amino ynones is reported under microwave irradiation in PEG-3400 as reaction matrix. The corresponding pure pyrrolin-4-ones were obtained in excellent yields (80-98%) directly after a straightforward precipitation-filtration workup, thus avoiding any chromatographic purification. The catalytic system was recycled and the chiral purity of all the products was also investigated.
Preparation of enantioenriched iodinated pyrrolinones by iodocyclization of α-amino-ynones
The unprecedented electrophilic iodo-mediated cyclization of α-amino-ynones afforded enantiomerically enriched β-iodopyrrolin-4-ones in excellent yields under mild conditions. The starting substituted α-amino-ynones were obtained from the chiral pool by selective mono-addition of an organolithium to optically pure N-protected carboxyanhydrides of amino acids (UNCAs).