Structure of prolylrapamycin: confirmation through a revised and detailed NMR assignment study.

A complete and detailed characterization of Rapamycin (1) and Prolylrapamycin (2) has been conducted by homo- and hetero-nuclear NMR experiments in DMSO-d 6 along with HRMS and FT-IR spectra and DSCs analyses. The NMR experiments allowed the assignment of every single proton and carbon atom belonging to the two structures and the definitive confirm of the presence of a pyrrolidine ring in Prolylrapamycin (2) in place of the piperidine ring that characterizes the structure of Sirolimus.