2662
T. Satoh et al. / Tetrahedron Letters 46 (2005) 2659–2662
O
S
LDA
H2C
Cl
δ 2.87 and 3.13
δ 3.17 and 3.72
O
Tol
OH
H
H
H
H
H
O
*
t-BuOK
H
S
O S(O)Tol
Tol
+
THF, -78 ˚C
t-BuOH-THF
0 ˚C, 93%
Cl
O S(O)Tol
H
82% (99%)
*
12
14
13
(13:14=3:1)
1) NaN3, NH4Cl
H2, Pd-C
COOCH3
NH2
NH2
13
COOCH3
N3
AcOEt
2) I2, KOH, CH3OH
COOCH3
(S)-(-)-16
[α]D24 -19.3 (c 0.57, EtOH)
98%
82%
15
(R)-(+)-16
[α]D21 +19.6 (c 0.27, EtOH)
( Lit,14 [α]D20 +20 (c 1.26, EtOH))
Scheme 3. Asymmetric synthesis of (R)-(+)-methyl 2-aminotetraline-2-carboxylate 16 from b-tetralone.
Tetrahedron 1994, 50, 1539; (c) Beller, M.; Eckert, M.
Angew. Chem., Int. Ed. 2000, 39, 1011.
The main product 13 was treated with NaN3 and the
resulting azido aldehyde was oxidized with I2 in metha-
nol to give the desired azido methyl ester 15 in 82% over-
all yield from 13. The enantiomeric excess of 15 was
determined to be over 99% by HPLC using CHIRAL-
CEL OD as a chiral stationary column. Finally, the cat-
alytic hydrogenation of 15 with Pd–C/H2 gave the
expected (R)-(+)-methyl 2-aminotetraline-2-carboxylate
(R)-(+)-16 in a quantitative yield. All the spectral data
and the specific rotation were highly consistent with
the reported value.14 From the minor sulfinyloxirane
14, the same treatment gave the enantiomer (S)-(À)-16
in a similar yield.
3. (a) Cativiela, C.; Diaz-de-Villegas, M. D. Tetrahedron:
Asymmetry 1998, 9, 3517; (b) Cativiela, C.; Diaz-de-
Villegas, M. D. Tetrahedron: Asymmetry 2000, 11, 645; (c)
Sano, S.; Nagao, Y. J. Synth. Org. Chem. Jpn. 2000, 58,
756; (d) Tanaka, M. J. Synth. Org. Chem. Jpn. 2002, 60,
125; (e) Belokon, Y. N.; Bhave, D.; DÕAddario, D.; Groaz,
E.; North, M.; Tagliazucca, V. Tetrahedron 2004, 60, 1849;
(f) Ooi, T.; Uematsu, Y.; Maruoka, K. Tetrahedron Lett.
2004, 45, 1675.
4. (a) Park, K.-H.; Kurth, M. J. Tetrahedron 2002, 58, 8629;
(b) Belvisi, L.; Colombo, L.; Manzoni, L.; Potenza, D.;
Scolastico, C. Synlett 2004, 1449.
5. Some recent reviews and papers concerning cyclic amino
acids (a) Czombos, J.; Aelterman, W.; Tkachev, A.;
Martins, J. C.; Tourwe, D.; Peter, A.; Toth, G.; Fulop,
F.; Kimpe, N. D. J. Org. Chem. 2000, 65, 5469; (b)
Kabalka, G. W.; Das, B. C.; Das, S. Tetrahedron Lett.
2001, 42, 7145; (c) Volk, F.-J.; Wagner, M.; Frahm, A. W.
Tetrahedron: Asymmetry 2003, 14, 497; (d) Truong, M.;
Lecornue, F.; Fadel, A. Tetrahedron: Asymmetry 2003, 14,
1063; (e) Kotha, S. Acc. Chem. Res. 2003, 36, 342; (f)
Andrei, M.; Undheim, K. Tetrahedron: Asymmetry 2004,
15, 53; (g) Meyer, U.; Breitling, E.; Bisel, P.; Frahm, A. W.
Tetrahedron: Asymmetry 2004, 15, 2029.
In conclusion, we have developed a new and versatile
method for the synthesis of a-quaternary a-amino acid
methyl esters from ketones in good overall yields. This
procedure was extended to an asymmetric synthesis
and we believe that the method presented here is one
of the most useful procedures for the asymmetric syn-
thesis of optically pure a-quaternary a-amino acid
methyl esters. We are continuing to study the scope
and limitation of this procedure.
6. Ota, H.; Chyouma, T.; Iso, S.; Satoh, T. Tetrahedron Lett.
2004, 45, 3903.
7. Satoh, T.; Taguchi, D.; Kurabayashi, A.; Kanoto, M.
Tetrahedron 2002, 58, 4217.
Acknowledgements
8. Dalcanale, E.; Montanari, F. J. Org. Chem. 1986, 51, 567.
9. Caron, M.; Sharpless, K. B. J. Org. Chem. 1985, 50, 1560.
10. Chini, M.; Crotti, P.; Macchia, F. Tetrahedron Lett. 1990,
31, 5641.
11. Inch, T. D.; Ley, R. V.; Rich, P. J. Chem. Soc. (C) 1968,
1693.
This work was supported by a grant from the Ministry
of Education, Culture, Sports, Science and Technology
of Japan to promote multi-disciplinary research project,
which is gratefully acknowledged.
12. Satoh, T.; Sato, T.; Oohara, T.; Yamakawa, K. J. Org.
Chem. 1989, 54, 3973.
References and notes
13. One equivalent of (R)-chloromethyl p-tolyl sulfoxide was
reacted with 1.4 equiv of b-tetralone. The yield was
calculated based on the sulfoxide.
1. Chemistry and Biochemistry of the Amino Acids; Barrett,
G. C., Ed.; Chapman and Hall: London, 1985.
14. Solladie-Cavallo, A.; Martin-Cabrejas, L.; Caravatti, G.;
Lang, M. Tetrahedron: Asymmetry 2001, 12, 967.
2. (a) Williams, R. M. Synthesis of Optically Active a-Amino
Acids; Pergamon: Oxford, 1989; (b) Duthaler, R. O.