3704
N. Valls et al. / Tetrahedron Letters 47 (2006) 3701–3705
IR (KBr): 3326, 1830, 1701 cmꢂ1 1H NMR (400 MHz,
;
J.; Hashemzadeh, M.; So, R. C.; Howell, A. R. Org. Lett.
2002, 4, 1719–1722; (c) Smith, N. D.; Wohlrab, A. M.;
Goodman, M. Org. Lett. 2005, 7, 255–258.
NOESY): 0.86 (d, J = 6.4 Hz, Me), 1.05 (d, J = 6.8 Hz,
Me), 1.88 (m, 1H, CH), 4.20 (dd, J = 10.4, 6.0 Hz, H-4),
5.13 (s, 2H, CH2), 5.50 (dd, J = 9.2, 6.0 Hz, H-3), 5.78 (d,
J = 9.2 Hz, NH), 7.35 (m, ArH); 13C NMR 17.2 (Me),
18.4 (Me), 28.6 (CH), 59.5 (C3), 67.8 (CH2), 82.7 (C4),
128.2, 128.4, 128.6, 135.5 (Ar), 155.3 (CO), 169.3
¨
13. (a) Shao, H.; Wang, S. H. H.; Lee, C.-W.; Osapay, G.;
Goodman, M. J. Org. Chem. 1995, 60, 2956–2957; (b)
Lall, M. S.; Karvellas, C.; Vederas, J. C. Org. Lett. 1999,
1, 803–806; (c) Smith, N. D.; Goodman, M. Org. Lett.
2003, 5, 1035–1037.
14. Chaltin, P.; Lescrinier, E.; Lescrinier, T.; Rozenski, J.;
Hendrix, C.; Rosemeyer, H.; Busson, R.; Van Aerschot,
A.; Herdewijn, P. Helv. Chim. Acta 2002, 85, 2258–
2283.
15. Schneider, A.; Rodrigues, O. E. D.; Paixao, M. W.;
Appelt, H. R.; Braga, A. L.; Wessjohann, L. A. Tetra-
hedron Lett. 2006, 47, 1019–1021.
16. For a review on the synthesis of optically active b-
lactones, see: Yang, H. W.; Romo, D. Tetrahedron 1999,
55, 6403–6434.
20
(C2). Compound 15: mp 85–86 ꢁC; ½aꢁD +27.2 (c 1.14,
CHCl3); IR (KBr): 3328, 1839, 1693 cmꢂ1 1H NMR
;
0.98 and 1.03 (2d, J = 6.6Hz, 2 · Me), 1.92 (m, CH), 4.29
(dd, J = 8.5, 4.3 Hz, H-4), 4.71 (dd, J = 8.5, 4.3 Hz, H-3),
5.09 (s, CH2), 5.99 (br s, NH), 7.32 (ArH); 13C NMR 16.9
(Me), 18.2 (Me), 31.8 (CH), 61.7 (C3), 67.9 (CH2), 84.6
(C4), 128.5, 128.7, 128.8, 135.8 (Ar), 155.6 (CO), 168.8
(C2). All new compounds were characterized by HRMS or
microanalysis.
27. For NMR data of N-Cbz-3-chlorothreonines, see: (2R,3S)
20
1
isomer 5, mp 116–118 ꢁC; ½aꢁD +3.2 (c 1.02, CH3OH); H
NMR (200 MHz, CDCl3, gCOSY) 1.63 (d, J = 7 Hz, H-
4), 4.37 (dq, J = 7, 3.1 Hz, H-3), 4.59 (d, J = 3.1 Hz, H-2),
5.12 (s, CH2), 5.76 (d, J = 8.4 Hz, NH), 7.35 (ArH); 13C
NMR (75 MHz, CDCl3) 21.3 (C4), 57.7 (C3), 59.3 (C2),
67.2 (CH2), 128.0, 128.2, 128.4, 136.0 (Ar), 156.0 (NCO),
17. (a) Pansare, S. V.; Huyer, G.; Arnold, L. D.; Vederas, J. C.
Org. Synth. 1992, 70, 1–9; (b) Pansare, S. V.; Arnold, L.
D.; Vederas, J. C. Org. Synth. 1992, 70, 10–17.
`
´
18. Moyano, A.; Pericas, M. A.; Valentı, E. J. Org. Chem.
1989, 54, 573–582.
20
19. For the synthesis of b-substituted N-protected a-amino-
b-lactones promoted by treatment of N-(o-nitrophenyl)-
sulfenyl derivatives of b-hydroxy a-amino acids with
4-bromobenzenesulfonyl chloride, see: Pu, Y.; Martin,
F. M.; Vederas, J. C. J. Org. Chem. 1991, 56, 1280–
1283.
170.3 (C1). (2R,3R) isomer 9, ½aꢁD +12.0 (c 1.7, CHCl3);
1H NMR (300 MHz, CDCl3, gCOSY) 1.53 (d, J = 6.8 Hz,
H-4), 4.88 (m, H-2 and H-3) [4.62 (dd, J = 3.1 Hz, H-2),
4.71 (dq, J = 6.8, 3.1 Hz, H-3) in CD3OD], 5.16 (s, CH2),
5.76 (d, J = 9.3 Hz, NH), 7.38 (s, ArH); 13C NMR
(75 MHz, CDCl3, gHSQC) 22.0 (C4), 57.8 (C2), 59.1
(C3), 67.6 (CH2), 128.0, 128.3, 128.5, 135.7 (Ar), 156.8
(NCO), 173.6 (C1).
20. Sliedregt, K. M.; Schouten, A.; Kroon, J.; Liskamp, R. M.
J. Tetrahedron Lett. 1996, 37, 4237–4240.
21. Corey and co-workers22 and Danishefsky and Endo23
have used this methodology (BOPCl instead of BOP) to
achieve the proteasome inhibitors salinosporamide A and
omuralide. Interestingly, in this context, Corey and co-
workers has reported a lactonization process promoted by
PH3PCl2.24
22. (a) Reddy, L. R.; Saravanan, P.; Corey, E. J. J. Am. Chem.
Soc. 2004, 126, 6230–6231; (b) Reddy, L. R.; Saravanan,
P.; Fournier, J.-F.; Reddy, B. V. S.; Corey, E. J. Org. Lett.
2005, 7, 2703–2705.
28. For the synthesis of (2R,3S)- and (2S,3R)-2-amino-3-
chlorobutanoic acid (b-chlorothreonines) by optical reso-
lution of the racemic form, see: Shiraiwa, T.; Miyazaki,
H.; Ohta, A.; Motonaka, K.; Kobayashi, E.; Kubo, M.;
Kurokawa, H. Chirality 1997, 9, 656–660.
29. (2R,3R)-b-Chlorothreonine (10) has been reported by
treatment of L-threonine with SOCl2 in dioxane solution:
Yamashita, K.; Inoue, K.; Kinoshita, K.; Ueda, Y.;
Murao, H. PCT WO 9933785. The methyl esters of
(2R,3R)- and (2S,3S)-2-amino-3-chlorobutanoic hydro-
chloride have been obtained from L- and D-allothreonine,
respectively, by treatment with PCl5: Plattner, Pl. A.;
23. Endo, A.; Danishefsky, S. J. J. Am. Chem. Soc. 2005, 127,
8298–8299.
24. Reddy, L. R.; Fournier, J.-F.; Reddy, B. V. S.; Corey, E. J.
Org. Lett. 2005, 7, 2699–2701; Reddy, L. R.; Fournier,
J.-F.; Reddy, B. V. S.; Corey, E. J. J. Am. Chem. Soc.
2005, 127, 8974–8976.
25. To our knowledge, this versatile b-lactone ring opening
has not previously been used in reactions promoted by
lithium chloride. For the synthesis of b-chlorothreonine by
ring opening of the corresponding b-lactone using
MgCl2ÆEt2O, see Ref. 9a.
Boller, A.; Frick, H.; Furst, A.; Hegedus, B.; Kirchenste-
¨ ¨
iner, H.; Majnoni, St.; Schla¨pfer, R.; Spiegelberg, H. Helv.
Chim. Acta 1957, 40, 1531–1552; For related work in the
racemic series, see: Srinivasan, A.; Stephenson, R. W.;
Olsen, R. K. J. Org. Chem. 1977, 42, 2256–2260.
30. To our knowledge there is only one precedent of b-
lactonization of 3-hydroxyleucine derivatives in the liter-
ature, involving the (2S,3S)-N,N-dibenzyl derivative:
Laib, T.; Chastanet, J.; Zhu, J. J. Am. Chem. Soc. 2002,
124, 583–590.
26. Analytical and spectroscopic data for b-lactones (NMR
data are recorded in CDCl3 at 300 and 75 MHz and
the assignments were aided by gCOSY, DEPT and
gHSQC experiments). Compound 4: mp 117–118 ꢁC;
31. Experimental procedure for 1: N-Benzyloxycarbonyloxy-
succinimide (539 mg, 2.16 mmol) and NaHCO3 (378 mg,
4.50 mmol) were added to a solution of 11 (Acros, 265 mg,
1.80 mmol) in H2O/THF 2:1 (6 mL). After stirring for
16 h at room temperature, the reaction mixture was
extracted with Et2O (3 · 5 mL) and the aqueous layer
was acidified until pH 2 and extracted with EtOAc
(4 · 15 mL). The combined organic phases were washed
with 1 N HCl (2 · 30 mL) and brine (2 · 30 mL), dried
with Na2SO4 and concentrated to afford the Cbz deriva-
20
½aꢁD +17.2 (c 1.03, CHCl3); IR (KBr): 3286, 1827,
1
1694 cmꢂ1; H NMR 1.42 (d, J = 6.2 Hz, Me), 4.83 (dq,
J = 6.2, 6.0 Hz, H-4), 5.13 (s, CH2), 5.45 (dd, J = 8.5,
6 Hz, H-3), 5.78 (d, J = 8.2 Hz, NH), 7 (ArH); 13C NMR
14.9 (Me), 60.3 (C3), 67.8 (CH2), 74.8 (C4), 128.2, 128.5,
128.6, 135.5 (Ar), 155.4 (CO), 168.8 (C2). Compound 8:
20
mp 114–115 ꢁC; ½aꢁD ꢂ40.3 (c 0.75, CHCl3); IR (KBr):
20
3313, 1847, 1833, 1699 cmꢂ1
;
1H NMR 1.60 (d,
tive (464 mg, 92%) as a colourless oil: ½aꢁD +3.9 (c 1.07,
J = 6.0 Hz, Me), 4.62 (dd, J = 7.5, 4.2 Hz, H-3), 4.75 (m,
H-4), 5.13 (s, CH2), 5.55 (d, J = 6.3 Hz, NH), 7.35 (ArH);
13C NMR 18.8 (Me), 64.3 (C3), 67.7 (CH2), 77.2 (C4),
128.3, 128.5, 128.6, 135.5 (Ar), 155.2 (CO), 167.7 (C2).
CHCl3); 1H NMR (400 MHz, CDCl3, COSY): 0.89 (d,
J = 6.8 Hz, 3H, H-5), 0.96 (d, J = 6.8 Hz, 3H, H-50), 1.71
(m, H-4), 3.76 (d, J = 9.2 Hz, H-3), 4.55 (d, J = 9.6 Hz, H-
2), 5.09 (s, OCH2Ph), 6.10 (d, J = 9.6 Hz, NH), 7.31 (m,
5H; ArH); 13C NMR (75 MHz, CDCl3, HSQC): 18.8 (C-
20
Compound 12: mp 79–80 ꢁC; ½aꢁD ꢂ12.8 (c 1.01, CHCl3);