Iterative organometallic addition to chiral hydroxylated cyclic nitrones: highly stereoselective syntheses of alpha,alpha'- and alpha,alpha-substituted hydroxypyrrolidines.
[reaction: see text]. Iteration of organometallic addition to chiral hydroxylated pyrroline N-oxides through an addition-oxidation-addition synthetic sequence allowed highly stereoselective double alkylation of pyrrolidine at C-2 or at C-2 and C-5 depending on the regioselectivity of the oxidation step. Application of this methodology has been exemplified by the synthesis of the all-substituted pyrrolidine alkaloid (-)-codonopsinine and of proline-type amino acid precursors possessing a quaternary stereogenic center, whose configuration can be controlled.
Dipartimento di Chimica Organica Ugo Schiff, Università di Firenze, via della Lastruccia 13, I-50019 Sesto Fiorentino (FI), Italy. andrea.goti@unifi.it
Andrea
A
Goti
Stefano
S
Cicchi
Vanni
V
Mannucci
Francesca
F
Cardona
Francesco
F
Guarna
Pedro
P
Merino
Tomas
T
Tejero