A simple and effective method to deprotect of sterically hindered steroid esters is described. Deprotection was carried out in MeOH in the presence of a catalytic amount of Et 3 N under high-pressure conditions. Enzymatic, anionite, and high-pressure methods are compared.

No abstract

1‐(N,N‐substituted‐aminiomethyl)spirobi[3‐oxo(2,5‐dioxa‐1‐silacyclopentan)]ates were investigated using NMR, X‐ray, and quantum‐chemical methods. The free activation parameters for the inversion of “ammonium‐amine nitrogen” and the chirality change at the pentacoordinated silicon were determined by dynamic NMR spectroscopy. The latter proceeds via the dissociation of SiO bonds. The results were confirmed by quantum‐chemical calculations, the experimental observation of cross‐peaks in 2D‐EXSY NMR spectra, and the spirocycle exchange reactions. Transition pathways between the different diastereomers in solution were analyzed.

No abstract