compound 13a being the unique isomerized product detected.
The amino vinyl ether 13a is a very useful building block for
further transformations: as an example it has been easily
deprotected to the amino aldehyde 14 and the latter oxidized18
to the b-amino acid 15 (Scheme 3). Both processes occur under
mild reaction conditions and without epimerization thus leading
to amino aldehydes and amino acids having the same optical
purity as the starting oxirane.
ology to other similar substrates could lead to a new approach to
a large variety of unsaturated a-amino acids.
Therefore, depending on the nature of the substituents on the
aziridine ring, the base-promoted rearrangement may disclose
new pathways to unnatural a- and b-amino acid precursors.
Investigation of the reactivity of a variety of aziridines with
superbases is in progress in our laboratory.
This work was supported by the Consiglio Nazionale delle
Ricerche, Rome.
As an additional example the symmetrical aziridine 9c,
obtained from diethyl tartrate in seven steps, has been also
converted to the amino vinyl ether 13c with good yield and high
Notes and references
1 A. Mordini, Comprehensive Organometallic Chemistry II, eds. E. W.
Abel, F. G. A. Stone and G. Wilkinson, Pergamon Press, Oxford, 1995,
vol. 11, p. 93.
2 A. Mordini, Advances in Carbanion Chemistry, ed. V. Snieckus, JAI
Press, Greenwich, CT, 1992, vol. 1, p. 1.
3 M. Schlosser, J. Organomet. Chem., 1967, 8, 9.
4 A. Mordini, S. Pecchi, G. Capozzi, A. Capperucci, A. Degl’Innocenti,
G. Reginato and A. Ricci, J. Org. Chem., 1994, 59, 4784.
5 A. Mordini, M. Valacchi, S. Pecchi, A. Degl’Innocenti and G. Reginato,
Tetrahedron Lett., 1996, 37, 5209.
6 A. Mordini, S. Bindi, S. Pecchi, A. Degl’Innocenti, G. Reginato and A.
Serci, J. Org. Chem., 1996, 61, 4374.
7 A. Mordini, S. Bindi, S. Pecchi, A. Capperucci, A. Degl’Innocenti and
G. Reginato, J. Org. Chem., 1996, 61, 4466.
8 A. Mordini, M. Valacchi, C. Nardi, S. Bindi, G. Poli and G. Reginato,
J. Org. Chem., 1997, 62, 8557.
Scheme 4 Reagents and conditions: i, LIDAKOR, pentane, 20% HMPA,
25 °C.
selectivity (Scheme 4). Compound 13c is a very useful building
block due to the large number of conveniently elaborable
functional groups.
The formation of vinyl ethers 13a and 13c is obviously due to
selective deprotonation of the methylene group adjacent to the
OMOM group and the aziridinyl ring. When we have applied
the same reaction conditions to the aziridine 9b, having an
additional acidic position (the benzylic methylene group), we
have found a different reaction pathway, leading this time to the
9 A. Thurner, F. Faigl, A. Mordini, A. Bigi, G. Reginato and L. Toke,
Tetrahedron, 1998, 54, 11597.
10 A. Thurner, F. Faigl, L. Toke, A. Mordini, M. Valacchi, G. Reginato and
G. Czira, Tetrahedron, 2001, 57, 8173.
11 A. Mordini, S. Bindi, A. Capperucci, D. Nistri, G. Reginato and M.
Valacchi, J. Org. Chem., 2001, 66, 3201.
12 Z. da Zhang and R. Scheffold, Helv. Chim. Acta, 1993, 76, 2602.
13 P. Müller and P. Nury, Helv. Chim. Acta, 2001, 84, 662.
14 H. M. I. Osborn and J. Sweeney, Tetrahedron: Asymmetry, 1997, 8,
1693.
15 S. Atkinson, Tetrahedron, 1999, 55, 1519.
Scheme 5 Reagents and conditions: i, LIDAKOR, pentane, 25 °C.
16 D. Tanner and P. Somfai, Tetrahedron Lett., 1987, 28, 1693.
17 A. Mordini, E. BenRayana, C. Margot and M. Schlosser, Tetrahedron,
1990, 46, 2401.
18 M. Zhao, J. Li, Z. Song, R. Desmond, D. M. Tschaen, E. J. J. Grabowski
and P. J. Reider, Tetrahedron Lett., 1998, 39, 5323.
cinnamyl amino alcohol 16 in a very selective manner (Scheme
5). Compound 16 is the precursor of the b,g-unsaturated a-
amino acid, phenylglycine and the extension of this method-
CHEM. COMMUN., 2002, 778–779
779