Abstract
We report a facile one-pot synthesis of chiral β-amino esters via direct reductive
amination of β-keto esters with ammonium acetate (NH4OAc) and H2 in the presence of chiral Ru-ClMeOBIPHEP catalysts using 2,2,2-trifluoroethanol (TFE)
as a solvent, leading to β-amino esters in high yields with high enantioselectivities
(up to 99% ee).
Key words
reductive amination - β-amino esters - β-keto esters - Ru-ClMeOBIPHEP catalyst
References
<A NAME="RG25805ST-1A">1a</A>
Enantioselective Synthesis of β-Amino Acids
Juaristi E.
Wiley-VCH;
New York:
1997.
<A NAME="RG25805ST-1B">1b</A>
Gademann K.
Hintermann T.
Schreiber JV.
Curr. Med. Chem.
1999,
6:
905
<A NAME="RG25805ST-1C">1c</A>
Gellman SH.
Acc. Chem. Res.
1998,
31:
173
<A NAME="RG25805ST-2A">2a</A>
Drexler H.-J.
You J.
Zhang S.
Fischer C.
Baumann W.
Spannenberg A.
Heller D.
Org. Process Res. Dev.
2003,
7:
355
<A NAME="RG25805ST-2B">2b</A>
Zhou Y.-G.
Tang W.
Wang W.-B.
Li W.
Zhang X.
J. Am. Chem. Soc.
2002,
124:
4952
<A NAME="RG25805ST-2C">2c</A>
Pena D.
Minnaard AJ.
de Vries JG.
Feringa BL.
J. Am. Chem. Soc.
2002,
124:
14552
<A NAME="RG25805ST-2D">2d</A>
Heller D.
Holz J.
Komarov I.
Drexler H.-J.
You J.
Drauz K.
Börner A.
Tetrahedron: Asymmetry
2002,
13:
2735
<A NAME="RG25805ST-2E">2e</A>
Heller D.
Drexler H.-J.
You J.
Baumann W.
Drauz K.
Krimmer H.-P.
Börner A.
Chem.-Eur. J.
2002,
8:
5196
<A NAME="RG25805ST-2F">2f</A>
Lubell WD.
Kitamura M.
Noyori R.
Tetrahedron: Asymmetry
1991,
2:
543
<A NAME="RG25805ST-3A">3a</A>
Hsiao Y.
Rivera NR.
Rosner T.
Krska SW.
Njolito E.
Wang F.
Sun Y.
Armstrong JD.
Grabowski EJJ.
Tillyer RD.
Spindler F.
Malan C.
J. Am. Chem. Soc.
2004,
126:
9918
<A NAME="RG25805ST-3B">3b</A>
Rosner, T.; Dormer, P. G.; Hsiao, Y.; Rivera, N.; Krska, S.; Hansen, K.; Armstrong,
J. D. III; Sun, Y.; Grabowski, E. J. J.; Volante, R. OMCOS-13, Poster, Geneva, Switzerland, 2005.
<A NAME="RG25805ST-3C">3c</A>
Kazuhiko M,
Xiaoyong Z, and
Takao S. inventors; Eur. Pat. Appl. EP 1386901.
<A NAME="RG25805ST-4A">4a</A>
Tararov VI.
Börner A.
Synlett
2005,
203
<A NAME="RG25805ST-4B">4b</A>
Kadyrov R.
Riermeier TH.
Angew. Chem. Int. Ed.
2003,
42:
5472
<A NAME="RG25805ST-4C">4c</A>
Tararov VI.
Kadyrov R.
Riermeier TH.
Fischer C.
Börner A.
Adv. Synth. Catal.
2004,
346:
561
<A NAME="RG25805ST-4D">4d</A>
Tararov VI.
Kadyrov R.
Riermeier TH.
Börner A.
Adv. Synth. Catal.
2002,
344:
200
<A NAME="RG25805ST-4E">4e</A>
Riermeier TH,
Haack K.-J,
Dingerdissen U,
Börner A,
Tararov VI, and
Kadyrov R. inventors; Ger. Offen. DE 19933611.
<A NAME="RG25805ST-4F">4f</A>
Kadyrov R.
Riermeier TH.
Dingerdissen U.
Tararov VI.
Börner A.
J. Org. Chem.
2003,
68:
4067
For (+)-ClMeOBIPHEP, see:
<A NAME="RG25805ST-5A">5a</A>
Laue C,
Schroeder G, and
Arlt D. inventors; Eur. Pat. Appl. EP 749973.
<A NAME="RG25805ST-5B">5b</A>
Drießen-Hölscher B.
Kralik J.
Agel F.
Steffens C.
Hu C.
Adv. Synth. Catal.
2004,
346:
979
<A NAME="RG25805ST-5C">5c</A>
Gerlach A.
Scholz U.
Speciality Chemicals Magazine
2004,
24:
37
<A NAME="RG25805ST-5D">5d</A>
Rampf, F. Proc. Chiral USA 2004, Scientific update, Mayfield, UK.
<A NAME="RG25805ST-6">6</A>
Using solvents such as EtOH, THF, CH2Cl2 or toluene led to the recovered starting material 2a.
For the reduction of β-keto esters, see:
<A NAME="RG25805ST-7A">7a</A>
Noyori R.
Asymmetric Catalysis in Organic Synthesis
John Wiley and Sons;
New York:
1994.
<A NAME="RG25805ST-7B">7b</A>
Ojima I.
Catalytic Asymmetric Synthesis
VCH;
Weinheim:
2000.
<A NAME="RG25805ST-7C">7c</A>
Tang W.
Zhang X.
Chem. Rev.
2003,
103:
3029
<A NAME="RG25805ST-7D">7d</A>
Blaser H.-U.
Pugin B.
Spindler F.
J. Mol. Catal. A: Chem.
2005,
231:
1
<A NAME="RG25805ST-7E">7e</A>
Ratovelomanana-Vidal V.
Girard C.
Touati R.
Tranchier JP.
Hassine BB.
Genêt JP.
Adv. Synth. Catal.
2003,
345:
261 ; and reference therein
<A NAME="RG25805ST-8">8</A>
Kitamura M.
Tokunaga M.
Noyori R.
J. Org. Chem.
1992,
57:
4053
<A NAME="RG25805ST-9">9</A>
The structure of ammonium salts of β-amino esters 5 were confirmed by 1H NMR.
<A NAME="RG25805ST-10">10</A>
Leflemme N.
Dallemagne P.
Rault S.
Synthesis
2002,
1740