Dear Prof. Landais,
I am pleased to answer your query and I send you the
General Procedure for the synthesis of pyrrolidin-2-ones
mediated by Mn(III).
Oxidative cyclisation of allylic amides:
To a stirred suspension of Mn(OAc)3.2H2O (2.4 g; 9 mmol)
and Cu(OAc)2.H2O (0.9 g; 4.5 mmol) in glacial acetic acid
(35 ml) was added the appropriate allylic amide (4.5
mmol), dissolved in glacial acetic acid (10 ml) and the
reaction mixture was stirred for 12 h at room
temperature. Water was added, and then Na2S2O8 10%
solution (20 ml). The resulting solution was extracted
with ethyl acetate (3 x 100 ml). the organic extracts
were washed with saturated NaHCO3 solution and dried
(Na2SO4). Removal of the solvent under reduced pressure
gave a residue which was purified by chromatography on
silica gel (cyclohexane:ethyl acetate 70:30) to give pure
diastereomers as colorless oils.
References for the Mn(III)-induced cyclization:
(a) Melikyan, G., Synthesis, 1993, 833-850.
(b) Iqbal, J.; Bhatia, B.; Nayyar, N. K., Chem. Rev.,
1994, 94, 519-564.
With Best Regards
Prof. Mario Orena