Asymmetric Baeyer—Villiger oxidation
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 9, September, 2004
1869
equilibrium mixture of transꢀ and cisꢀβꢀisomers in the
presence of propaneꢀ1,3ꢀdiol. It has been considered that
the axial phenoxy group is first replaced by the 1,3ꢀdiol
and the equatorial water molecule is replaced intraꢀ
molecularly by the other hydroxy group of the diol to
form a sixꢀmembered chelate; the concomitant proton
transfer promotes dissociation of the other phenoxy group
(Scheme 25). The formation of a five membered ring is
more favorable than sixꢀmembered ring formation, and
the Criegee adduct forms a fiveꢀmembered chelate. Thus,
it is likely that 14 adopts the cisꢀβꢀconfiguration and effiꢀ
ciently recognizes a structural change of the substrate, as
expected.
Palladium(II)—2ꢀ(phosphinophenyl)pyridine comꢀ
plex 15 can serve as the catalyst for the BV oxidation24
(Scheme 26). It has been proposed that the conformation
of the chelated Criegee intermediate is regulated to allow
the enantiotopos selective σ—σ* interaction with the chiral
ligand 15.
Studies into the biological and chemical asymmetꢀ
ric Baeyer—Villiger oxidation reactions have revealed
that their stereochemistry is mainly determined by
recognition of the structure of the Criegee intermediꢀ
ate and by regulation of the stereoelectronic requireꢀ
ments in its migration. Using a trialꢀandꢀerror proꢀ
cess along this line, some studies have achieved a high
level of enantiotopos selectivity and regiodivergent parꢀ
allel kinetic resolution in the BV oxidation of proꢀ
chiral and racemic ketones, respectively. However, the
chemist´s understanding of how a molecular catalyst recꢀ
ognizes a transition state structure and controls the conꢀ
formation of the transition state is still immature. Accuꢀ
mulation of such knowledge will pave the way for highly
efficient BV oxidation using a reasonably designed moꢀ
lecular catalyst.
Scheme 25
References
1. G. R. Krow, Org. React., 1993, 43, 251.
2. R. Criege, J. Liebigs Ann. Chem., 1948, 560, 127.
3. (a) V. Alphand and R. Furstoss, in Handbook of Enzyme
Catalysis in Organic Synthesis, Eds K. Drauz, and
H. Waldmann, VCH Publishers, Weinheim, 1995, p. 744;
(b) S. M. Roberts and P. W. H. Wan, J. Mol. Cat. B: Enꢀ
zymatic, 1998, 4, 111—136; (c) D. R. Kelly, Chemica
Oggi/Chemical Today, 2000, 18, 33, 52.
Scheme 26
4. V. Alphand, A. Archelus, and R. Furstoss, Tetrahedron Lett.,
1989, 30, 3663.
5. F. Bertozzi, P. Crotti, F. Macchia, M. Pineshi, and B. L.
Feringa, Angew. Chem., Int. Ed. Engl., 2001, 40, 930.
6. S.ꢀI. Murahashi, S. Ono, and Y. Imada, Angew. Chem., Int.
Ed., 2002, 41, 2366.
7. C. Bolm, G. Schlingloff, and K. Weickhard, Angew. Chem.,
Int. Ed., 1994, 33, 1848.
8. A. Gusso, C. Baccin, F. Pinna, and G. Strukul, Organomeꢀ
tallics, 1994, 13, 3442.
9. C. Bolm and G. Schlingloff, J. Chem. Soc., Chem. Commun.,
1995, 1247.
10. (a) M. Lopp, A. Paju, T. Kanger, and T. Pehk, Tetrahedron
Lett., 1996, 37, 7583; (b) C. Bolm, G. G. Schlingloff, and
F. Bienewald, J. Mol. Cat. A; Chem., 117, 347; (c) C. Bolm,
K. K. Luong, and G. Schlingloff, Synlett., 1997, 1151;
(d) C. Bolm and O. Beckmann, Chirality, 2000, 12, 523;
(e) T. Shinohara, F. Fujioka, and H. Kotsuki, Heterocycles,
2001, 55, 237.
11. C. Bolm, O. Beckmann, A. Cosp, and C. Palazzi, Synlett.,
2001, 1461.
12. C. Bolm, O. Beckmann, and C. Palazzi, Can. J. Chem.,
2001, 79, 1593.
i. Pd(SbF6)2ꢀ15 (5 mol.%), UHP, THF, –60 °C
ii. Pd(SbF6)2ꢀ15 (5 mol.%), UHP, THF, –40 °C