Abstract
Aldimines, ketimines, and enaminones can be obtained under erbium(III) triflate catalysis. The reaction mechanism is that typical of imine synthesis. The role of the catalyst is demonstrated for the synthesis of aromatic imines. In contrast to CeCl3 /NaI addition to unsaturated aldehydes, which results in Michael addition, no Michael adduct was observed under erbium(III) triflate catalysis.
Key words
imines - enaminones - erbium triflate - Lewis acids - catalysis
References
1
Schiff H.
Annals
1864,
131:
118
2
The Chemistry of the Carbon-Nitrogen Double Bond
Patai S.
Wiley Interscience;
New York:
1970.
Imines:
3a
Moffett RB.
Org. Synth., Coll. Vol. 4
Rabjohn N.
J. Wiley & Sons Inc.;
New York:
1963.
p.605
3b
Weingarten H.
Chupp JP.
White WA.
J. Org. Chem.
1967,
32:
3246
Enaminones:
3c
Singh HRV.
Tandon JP.
J. Prakt. Chem.
1979,
321:
151
3d
Baraldi PG.
Simoni D.
Manfredini S.
Synthesis
1983,
902
3e
Ferraz HMC.
Oliveira EO.
Payret-Arrua ME.
Brandt CA.
J. Org. Chem.
1995,
60:
7357
3f
Amougay A.
Letsch O.
Pete JP.
Tetrahedron
1996,
52:
2405
3g
Valduga CL.
Squinzani A.
Braibante HS.
Braibante MEF.
Synthesis
1998,
1019
3h
Arend M.
Westermann B.
Risch N.
Angew. Chem. Int. Ed.
1998,
37:
1044
Imine syntheses using different catalysts. Molecular sieves:
4a
Taguchi K.
Wesheimer FH.
J. Org. Chem.
1971,
36:
1570
Dehydrating solvents:
4b
Love BE.
Ren J.
J. Org. Chem.
1993,
58:
556
4c
Look GC.
Murphy MM.
Campbell DA.
Gallop MA.
Tetrahedron Lett.
1995,
36:
2937
4d
Vaas RS.
Dudas J.
Varma RS.
Tetrahedron Lett.
1999,
40:
4951
ZnCl2 :
4e
Billman JH.
Tai KM.
J. Org. Chem.
1958,
23:
535
Ti(IV):
4f
White WA.
Weingarten H.
J. Org. Chem.
1967,
32:
213
4g
Moretti I.
Torre G.
Synthesis
1970,
141
4h
Jennings WB.
Lovely CJ.
Tetrahedron Lett.
1988,
29:
3725
4i
Armstrong JD.
Wolfe CN.
Keller JL.
Linch J.
Bhupathy M.
Volante RP.
de Vita RJ.
Tetrahedron Lett.
1997,
38:
1531
MgSO4 :
4j
Branchaud BP.
J. Org. Chem.
1983,
48:
3531
MgClO4 :
4k
Chakraboti AK.
Bhagat S.
Rudrawar S.
Tetrahedron Lett.
2004,
45:
7641
Al2 O3 :
4l
Texier-Bullet F.
Synthesis
1986,
679
Clay:
4m
Varma RS.
Dahiya R.
Kumar S.
Tetrahedron Lett.
1997,
38:
2039
CuSO4 :
4n
Liu G.
Cogan DA.
Owens TD.
Tang TP.
Ellman JA.
J. Org. Chem.
1999,
64:
1278
Ionic liquid:
4o
Andrade CKZ.
Takada SCS.
Alves LM.
Rodrigues JP.
Suarez PAZ.
Brandão RF.
Soares VCD.
Synlett
2004,
2135
Enaminone syntheses using different catalysts. Al2 O3 :
5a
Valduga CL.
Braibante HS.
Braibante MEF.
J. Heterocycl. Chem.
1998,
35:
189
SiO2 under microwave irradiation:
5b
Rechsteimer B.
Texier-Bullet F.
Hamelin J.
Tetrahedron Lett.
1993,
34:
5071
Clay:
5c
Braibante MEF.
Braibante HS.
Missio L.
Andricopulo A.
Synthesis
1994,
898
NaAuCl4 :
5d
Arcadi A.
Bianchi G.
Di Giuseppe S.
Marinelli F.
Green Chem.
2003,
5:
64
Amine in water:
5e
Stefani HA.
Costa IM.
de O Silva D.
Synthesis
2000,
1526
Ultrasound:
5f
Brandt CA.
da Silva ACMP.
Pancote CG.
Brito CH.
da Silveira MAB.
Synthesis
2004,
1557
Zn(ClO4 )2 :
5g
Bartoli G.
Bosco M.
Locatelli M.
Marcantoni E.
Melchiorre P.
Sambri L.
Synlett
2004,
239
CeCl3 :
5h
Khodaei MM.
Khosropour AR.
Kookhazadeh M.
Synlett
2004,
1980
6a
Kobayashi S.
Sugiura M.
Kitagawa H.
Lam WW.-L.
Chem. Rev.
2002,
102:
2227
6b
Kobayashi S.
Menabe K.
Acc. Chem. Res.
2002,
35:
209
6c
Kobayashi S.
Nagayama S.
Busujima T.
J. Am. Chem. Soc.
1998,
120:
8287
7a
Tsuruta H.
Yamaguchi K.
Imamoto T.
Tetrahedron
2003,
59:
10419
7b
Tsuruta H.
Yamaguchi K.
Imamoto T.
Chem. Commun.
1999,
1703
8a
Firouzabadi H.
Iranpoor N.
Sobhani S.
Synthesis
2004,
2692
8b
Aspinall HC.
Bissett JS.
Greeves N.
Levin D.
Tetrahedron Lett.
2002,
43:
323
9a
Procopio A.
Dalpozzo R.
De Nino A.
Maiuolo L.
Russo B.
Sindona G.
Adv. Synth. Catal.
2004,
346:
1465
9b
Dalpozzo R.
De Nino A.
Maiuolo L.
Nardi M.
Procopio A.
Tagarelli A.
Synthesis
2004,
496
9c
Procopio A.
Dalpozzo R.
De Nino A.
Nardi M.
Sindona G.
Tagarelli A.
Synlett
2004,
2633
9d
Procopio A.
Dalpozzo R.
De Nino A.
Maiuolo L.
Nardi M.
Russo B.
Adv. Synth. Catal.
2005,
347:
1447
9e
Procopio A.
Dalpozzo R.
De Nino A.
Maiuolo L.
Nardi M.
Romeo G.
Org. Biomol. Chem.
2005,
4129
9f
Procopio A.
Dalpozzo R.
De Nino A.
Nardi M.
Russo B.
Tagarelli A.
Synthesis
2006,
332
10 Some imines were unstable and a one-pot reduction step was necessary for their identification. This was realized by addition of a THF solution of LiBH4 to the mixture, after monitoring the disappearance of the reactants by GC-MS analysis.
11
Layer RW.
Chem. Rev.
1963,
63:
489
12
Bartoli G.
Bartolacci M.
Giuliani A.
Marcantoni E.
Massaccesi M.
Torreggiani E.
J. Org. Chem.
2005,
70:
169
13 A solution of Er(OTf)3 in water is only weakly acidic (pH 5.9) and the aqueous layers from the work-up were even less acidic (pH 6.7); such values are not compatible with triflic acid being the active catalyst.
14 LD50 of erbium salts is 4417 mg/Kg against 4000 mg/Kg for NaCl.
15 It is likely that the catalyst can be recovered in higher yields when the reaction is scaled up; we recovered the catalyst in ÷90% yield.
16
Bull SD.
Davies SG.
Fenton G.
Mulvaney AW.
Prasad RS.
Smith AD.
J. Chem. Soc., Perkin Trans. 1
2000,
3765
17
Nongkunsarn P.
Ramsden CA.
Tetrahedron
1997,
53:
3805
18
Forlani L.
Sintoni M.
Todesco PE.
Gazz. Chim. Ital.
1986,
116:
229
19
Egger H.
Djerassi CJ.
J. Am. Chem. Soc.
1973,
95:
3710
20
Johansson A.
Abrahamsson P.
Davidsson O.
Tetrahedron: Asymmetry
2003,
14:
1261
21
Yoon NM.
Kim EG.
Son HS.
Choi J.
Synth. Commun.
1993,
23:
1595
22
Sassaman MB.
Tetrahedron
1996,
52:
10835
23
Jones D.
Roberts A.
Cavell K.
Keim W.
Englert U.
Kelton BW.
White AH.
J. Chem. Soc., Dalton Trans.
1998,
255
24
Dudek GO.
Holm RH.
J. Am. Chem. Soc.
1962,
84:
2691
25
Bartoli G.
Cimarelli C.
Palmieri G.
Bosco M.
Dalpozzo R.
Synthesis
1990,
895
26
Kashima C.
Aoyama H.
Yamamoto Y.
Nishio T.
Yamada K.
J. Chem. Soc., Perkin Trans. 2
1975,
665
27
Boatman S.
Hauser CR.
J. Org. Chem.
1966,
31:
1785
28
Bartoli G.
Cimarelli C.
Dalpozzo R.
Palmieri G.
Tetrahedron
1995,
51:
8613