Conclusive evidence for a retention-retention pathway for the molybdenum-catalyzed asymmetric alkylation.
Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(O2COMe)-CH=CHD (1a), (Z)-(R)-PhCH(O2COMe)CH=CHD (2a), and linear carbonate (E)-(S)-PhCH=CHCHD(O2COMe) (12) were employed as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand complex 10 derived from the mixed benzamide/picolinamide of (S,S)-trans-diaminocyclohexane and (norbornadiene)Mo(CO)4. X-ray crystallography, along with solution NMR structural analysis of the pi-allyl intermediate and competition experiments, conclusively established the reaction proceeded via a retention-retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed via an inversion-inversion pathway.
Lloyd-Jones
Guy C
GC
School of Chemistry, University of Bristol, Bristol BS8 ITS, UK. guy.lloyd-jones@bristol.ac.uk
Krska
Shane W
SW
Hughes
David L
DL
Gouriou
Laure
L
Bonnet
Veronique D
VD
Jack
Kevin
K
Sun
Yongkui
Y
Reamer
Robert A
RA