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DOI: 10.1055/s-0029-1218001
Asymmetric α-Amination of Chiral Protected β-Hydroxyaldehydes Catalyzed by Proline
Publikationsverlauf
Publikationsdatum:
08. Oktober 2009 (online)
Abstract
Proline-catalyzed α-amination of a variety of chiral β-hydroxyaldehydes followed by reduction step afforded the corresponding chiral 2-hydrazino-1,3-diols in good yields, enantioselectivities and diastereoselectivities.
Key words
amination - organocatalysis - diastereoselectivity - β-hydroxyaldehyde - 2-hydrazino-1,3-diol - azodicarboxylate
- 1
Xu LW.Luo J.Lu X. Chem. Commun. 2009, 1807 - 2
Mukherjee S.Yang JW.Hoffmann S.List B. Chem. Rev. 2007, 107: 5471 - 3 For either diastereoselective or
organocatalytic electrophilic α-amination, see:
Greck C.Drouillat B.Thomassigny C. Eur. J. Org. Chem. 2004, 1377 - 4
Bogevig A.Juhl K.Kumaragurubaran N.Zhuang W.Jørgensen KA. Angew. Chem. Int. Ed. 2002, 41: 1790 - 5
List B. J. Am. Chem. Soc. 2002, 124: 5656 -
6a
Vogt H.Vanderheiden S.Bräse S. Chem. Commun. 2003, 2448 -
6b
Baumann T.Vogt H.Bräse S. Eur. J. Org. Chem. 2007, 266 -
6c
Baumann T.Bächle M.Hartmann C.Bräse S. Eur. J. Org. Chem. 2008, 2207 -
7a
Kumaragurubaran N.Juhl K.Zhuang W.Bogevig A.Jørgensen KA. J. Am. Chem. Soc. 2002, 124: 6254 -
7b
Liu T.Cui H.Zhang Y.Jiang K.Du W.He Z.Chen Y. Org. Lett. 2007, 9: 3671 -
8a
Dahlin N.Bøgevig A.Adolfsson H. Adv. Synth. Catal. 2004, 346: 1101 -
8b
Thomassigny C.Prim D.Greck C. Tetrahedron Lett. 2006, 47: 1117 -
8c
Hayashi Y.Arakate S.Imai Y.Hibino K.Chen QY.Yamaguchi J.Uchimaru T. Chem. Asian. J. 2008, 3: 225 -
9a
de Figueiredo RM.Christmann M. Eur. J. Org. Chem. 2007, 2575 ; and references cited therein -
9b
Sudalai A. Tetrahedron 2007, 63: 9758 -
9c
George S.Suryavanshi GS.Sudalai A. Tetrahedron Lett. 2008, 49: 6791 -
9d
Kalch D.De Rycke N.Moreau X.Greck C. Tetrahedron Lett. 2009, 50: 492 -
9e
Nishikawa Y.Kitajima M.Kogure N.Takayama H. Tetrahedron 2009, 65: 1608 - 11 To determine the relative configuration
of anti-2, we synthesized
this compound via diastereoselective electro-philic amination method
from ethyl (R)-3-hydroxybutyrate using
LDA, ZnBr2 and DBAD. For this reaction, see:
Genêt JP.Jugé S.Mallart S. Tetrahedron Lett. 1998, 29: 6765 - 13
Ait-Youcef R.Kalch D.Moreau X.Thomassigny C.Greck C. Lett. Org. Chem. 2009, 6: 377 - 14
Franzén J.Marigo M.Fielenbach D.Kjrsgaard A.Jørgensen KA. J. Am. Chem. Soc. 2005, 127: 18296 - 16
Bourdreux Y.Drouillat B.Greck C. Synlett 2005, 2086 - 17
Poupardin O.Greck C.Genêt JP. Synlett 1998, 1279
References and Notes
3-tert-Butyldimethylsilyloxybutanal (1) was synthesized in two steps (TBS protection and DIBAL-H reduction of the ester moiety) from ethyl 3-hydroxybutyrate commercially available in both enantiomeric forms.
12General Procedure for the Organocatalytic α-Amination: Dibenzylazodicarboxylate (1 mmol) and d- or l-proline (0.2 mmol, 20 mol%) in MeCN (10 mL) were treated with an aldehyde (1.5 mmol) at r.t. The reaction mixture was stirred at this temperature until the yellow color of the azodicarboxylate had disappeared. The mixture was treated with EtOH (10 mL) and NaBH4 (40 mg) and was stirred for 5 min at 0 ˚C. The reaction was worked up with aq NH4Cl solution and EtOAc. The organic layers were dried (MgSO4), filtered, and concentrated. Medium-pressure column chromatography on silica gel with EtOAc-pentane mixture (1:4) gave the desired anti- or syn-2-hydrazino-1,3-diol as a single diastereomer.
15
Characterization
of Selected Compounds:
Compound 2: ¹H
NMR (300 MHz, CDCl3): δ = 0.01-0.05 (m,
6 H), 0.86 (s, 9 H), 1.08-1.16 (m, 3 H), 3.51-3.99
(m, 4 H), 4.15-4.33 (m, 1 H), 5.16-5.29 (m, 4
H), 6.54 (s, 1 H), 7.28-7.37 (m, 10 H). ¹³C
NMR (75 MHz, CDCl3): δ = -5.1, -4.3,
17.7, 21.1, 25.6, 59.1, 59.6, 66.3, 67.0, 67.4, 68.1, 68.3, 68.5,
127.5, 127.7, 128.0, 128.1, 128.3, 128.4, 128.5, 135.0, 135.4, 135.6,
156.0, 157.0, 158.2, 158.9. MS (ESI): m/z = 525.4 [M + Na+].
IR: 3409, 3272, 2955, 2856, 1722, 1268, 1097, 833, 777, 696 cm-¹.
Anal. Calcd for C26H38N2O6Si:
C, 62.12; H, 7.62; N, 5.57. Found: C, 62.06; H, 7.55; N, 5.48. [α]D
²5 -25
(c = 1, CH2Cl2)
for (S,R)-2; [α]D
²5 +24
(c = 1, CH2Cl2)
for (R,S)-2.
Compound 3: ¹H
NMR (300 MHz, CDCl3): δ = (-0.01)-0.05 (m,
6 H), 0.81-0.82 (m, 9 H), 1.08-1.18 (m, 3 H),
3.48-4.04 (m, 4 H), 4.20-4.38 (m, 1 H), 5.14-5.30
(m, 4 H), 6.69-6.74 (m, 1 H), 7.32-7.37 (m, 10
H). ¹³C NMR (75 MHz, CDCl3): δ = -5.3, -5.2, -4.3, -4.2,
17.6, 21.2, 21.3, 25.5, 25.6, 59.7, 59.8, 64.1, 65.8, 68.1, 68.2,
68.5, 68.7, 127.6, 128.0, 128.1, 128.2, 128.4, 128.5, 135.2, 135.5,
135.8, 156.3, 156.9, 157.6, 158.2. MS (ESI): m/z = 525.4 [M + Na+].
IR: 3401, 3270, 2953, 2855, 1721, 1256, 1072, 836, 776, 696 cm-¹. Anal.
Calcd for C26H38N2O6Si:
C, 62.12; H, 7.62; N, 5.57. Found: C, 62.02; H, 7.35; N, 5.55. [α]D
²5 -3
(c = 1, CH2Cl2) for
(R,R)-3; [α]D
²5 +3
(c = 1, CH2Cl2)
for (S,S)-3.