Y. Saito et al. / Tetrahedron Letters 46 (2005) 1277–1279
1279
Acknowledgements
Synthesis. Construction of Chiral Molecules Using Amino
Acids; John Wiley & Sons: New York, 1987.
9
. Green, T. W.; Wuts, P. G. M. Protective Groups in Organic
Synthesis, Third ed.; John Wiley & Sons: New York, 1999.
This work was supported in part by a Grant-in-Aid for
Scientific Research (No. 15590019) from Ministry of
Education, Sciences, Sports, and Culture of Japan.
1
0. Typical procedure: The procedure for the preparation of
S-N-benzyloxycarbonyl)alanine allyl ester 2d, is repre-
(
sentative of all cases. BBDI (1.2mmol) was added
to a solution of (S)-N-benzyloxycarbonyl)phenylalanine
(1 mmol) in dioxane (5 mL) with stirring at room temper-
ature. The reaction mixture was stirred for 30 min. To the
reaction mixture was added allyl alcohol (1.1 mmol). The
reaction mixture was stirred for 5 h and then concentrated.
After the addition of ethyl acetate, the organic phase was
washed twice with 5% HCl and brine. The organic layers
References and notes
1
. (a) Otera, J. Esterification Methods Reaction and Applica-
tions; Wiley-VCH: Weinheim, 2003; (b) Multzer, J. Com-
prehensive Organic Functional Group Transformations.
In Carboxylic Esters and Lactones; Moody, C. J., Ed.
1
995; Pergamon: Oxford; Vol. 6, p 121; (c) Sutherland, I.
4
were dried (MgSO ) and the solvent evaporated to give the
O. In Comprehensive Organic Chemistry; Barton, D. H. R.,
Ollis, W. D., Eds.; Pergamon: Oxford, 1979; Vol. 2, p 869.
. Multzer, J. In Comprehensive Organic Synthesis; Trost, B.
M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 6,
p 323.
. (a) Ishihara, K.; Ohhara, S.; Yamamoto, H. Sciences 2000,
290, 1140; (b) Manabe, K.; Sun, X.-M.; Kobayashi, S.
J. Am. Chem. Soc. 2001, 123, 10101.
. (a) Shiina, I.; Kubota, M.; Oshiumi, H.; Hashizume, M. J.
Org. Chem. 2004, 69, 1822; (b) Disadee, W.; Watanabe, T.;
Ishikawa, T. Synlett 2003, 115; (c) Isobe, T.; Ishikawa, T.
J. Org. Chem. 1999, 64, 6984; (d) Inanaga, J.; Hirata, K.;
Saeki, H.; Katsuki, T.; Yamaguchi, M. Bull. Chem. Soc.
Jpn. 1979, 52, 1989.
. (a) Ouchi, H.; Saito, Y.; Yamamoto, Y.; Takahata, H.
Org. Lett. 2002, 4, 585; (b) BBDI, like Reissert reaction,
2
was readily prepared by exposure of isoquinoline to Boc O
in quantitative yield in large scales (0.3–0.5 mol) and can
be stored at room temperature for over half a year without
any decomposition.
. (a) Zacharie, B.; Connolly, T. P.; Penney, C. L. J. Org.
Chem. 1995, 60, 7072; (b) Huttenloch, O.; Laxman, E.;
Waldmann, H. Chem. Commun. 2002, 673; (c) Belleau, B.;
Malek, G. J. Am. Chem. Soc. 1968, 90, 1651.
crude compound, which was purified by chromatography
on a short column to yield 2h (296 mg, 91%), colorless
À1
1
2
3
4
liquid; IR (KBr): 1714, 1728, 3340 cm
;
H NMR
(270 MHz, CDCl ) d: 3.04–3.19 (2H, m), 4.59 (2H, d,
3
J = 5.8 Hz), 4.60–4.71 (1H, m), 5.08 (2H, s), 5.21–5.35
(3H, m), 5.77–5.91 (1H, m), 7.07–7.19 (2H, m), 7.24–7.38
2
1
11
25
(8H, m); ½aꢀ À14.8 (c 1.3, MeOH) [lit. ½aꢀ À15.6 (c
D
D
2.03, MeOH)]; MS (EI) m/z 339 (M ); HRMS m/z Calcd
+
+
4
for C20H21NO (M ) 339.1471. Found: 339.1458.
11. Takeda, K.; Akiyama, A.; Nakamura, H.; Takizawa, S.;
Mizuno, Y.; Takayanagi, H.; Harigaya, Y. Synthesis 1994,
1063–1066.
12. The reaction of N-Cbz-alanine (1 mmol) with allyl alcohol
(1 mmol) using 1-isopropoxy-2-ethoxycarbonyl-1,2-dihy-
droisoquinoline (1.2mmol) provided N-Cbz amino allyl
ester (47%) together with N-Cbz amino isopropyl ester
(12%) and N-Cbz amino ethyl ester (30%) as byproducts.
5
2
3
13. The specific optical rotations of samples of (2a)½aꢀ À33.0
D
1
4
25
D
(c 1.2, CH
3
OH), lit. ½aꢀ À32.7 (c 1.3, CH
3
OH), 2b
2
7
14
23
D
½aꢀ À32.6 (c 1.5, CH
3
OH), lit. ½aꢀ À32.2 (c 1.0,
D
CH OH) were in good agreement with literature values.
6
7
3
In fact, the enantiomeric purities of 2a, 2b and 2h were
>99% ee, as determined by chiral HPLC analysis (Chiral-
cel OD column, 95:5 hexane/2-propanol, 1.0 mL/min) for
2a,b and (Chiralcel OJ column) for 2h.
. Carboxylate activation: (a) Jouin, P.; Castro, B.; Zeggaf,
C.; Pantaloni, A.; Senet, J. P.; Lecolier, S.; Sennyey, G.
Tetrahedron Lett. 1987, 28, 1661; nucleophilic displace-
ment: (b) Wang, S.-S.; Gisin, B. F.; Winter, D. P.;
Makofske, R.; Kulesha, I. D.; Tzougraki, C.; Meienhofer,
J. J. Org. Chem. 1977, 42, 1286; (b) Bocchi, V.; Casnati,
G.; Dossena, A.; Marchelli, R. Synthesis 1979, 957; (c)
Bocchi, V.; Casnati, G.; Dossena, A.; Marchelli, R.
Synthesis 1979, 961.
14. Gibson, F. S.; Park, M. S.; Rapoport, H. J. Org. Chem.
1994, 59, 7503.
15. In most of examples of esterification of N-protected a-
amino acids, additives such as DMAP were used. In case
using DMAP-catalyzed carbodiimide condensation, some
racemization was observed (a) Neises, B.; Steglich, W.
Angew. Chem., Ed. Engl. 1978, 17, 552; (b) Atherton, E.;
Benoiton, N. L.; Brown, E.; Shephard, R. C.; Williams, B.
J. Chem. Soc., Chem. Commun. 1981, 336.
8
. N-Protected amino acid esters were used as chiral educts
(
a) Sardina, F. J.; Rapoport, H. Chem. Rev. 1996, 96,
825; (b) Coppola, G. M.; Schuster, H. F. Asymmetric
16. Results including esterification of other carboxylic acids
will be published in due course.
1