Erbium(III) Triflate: A Valuable Catalyst for the Synthesis of Aldimines, Ketimines, and Enaminones

Renato Dalpozzo; Antonio De Nino; Monica Nardi; Beatrice Russo; Antonio Procopio

doi:10.1055/s-2006-926378

PAPER

Erbium(III) Triflate: A Valuable Catalyst for the Synthesis of Aldimines, Ketimines, and Enaminones

Renato Dalpozzo*^a, Antonio De Nino^a, Monica Nardi^a, Beatrice Russo^b, Antonio Procopio^b
^a Dipartimento di Chimica, Univesità della Calabria, Ponte Bucci, cubo 12C, 87030 Arcavacata di Rende (Cs), Italy
Fax: +39(0984)493077; e-Mail: dalpozzo@unical.it;
^b Dipartimento di Scienze Farmaco-Biologiche, Università della Magna Graecia, Complesso Ninì Barbieri, 88021 Roccelletta di Borgia (Cz), Italy

Abstract

All articles of this category

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

Full Text

References

<A NAME="RZ20105SS-1">1</A> Schiff H. Annals 1864, 131: 118

<A NAME="RZ20105SS-2">2</A> The Chemistry of the Carbon-Nitrogen Double Bond Patai S. Wiley Interscience; New York: 1970.

Imines:

<A NAME="RZ20105SS-3A">3a</A> Moffett RB. Org. Synth., Coll. Vol. 4 Rabjohn N. J. Wiley & Sons Inc.; New York: 1963. p.605

<A NAME="RZ20105SS-3B">3b</A> Weingarten H. Chupp JP. White WA. J. Org. Chem. 1967, 32: 3246

Enaminones:

<A NAME="RZ20105SS-3C">3c</A> Singh HRV. Tandon JP. J. Prakt. Chem. 1979, 321: 151

<A NAME="RZ20105SS-3D">3d</A> Baraldi PG. Simoni D. Manfredini S. Synthesis 1983, 902

<A NAME="RZ20105SS-3E">3e</A> Ferraz HMC. Oliveira EO. Payret-Arrua ME. Brandt CA. J. Org. Chem. 1995, 60: 7357

<A NAME="RZ20105SS-3F">3f</A> Amougay A. Letsch O. Pete JP. Tetrahedron 1996, 52: 2405

<A NAME="RZ20105SS-3G">3g</A> Valduga CL. Squinzani A. Braibante HS. Braibante MEF. Synthesis 1998, 1019

<A NAME="RZ20105SS-3H">3h</A> Arend M. Westermann B. Risch N. Angew. Chem. Int. Ed. 1998, 37: 1044

Imine syntheses using different catalysts. Molecular sieves:

<A NAME="RZ20105SS-4A">4a</A> Taguchi K. Wesheimer FH. J. Org. Chem. 1971, 36: 1570

Dehydrating solvents:

<A NAME="RZ20105SS-4B">4b</A> Love BE. Ren J. J. Org. Chem. 1993, 58: 556

<A NAME="RZ20105SS-4C">4c</A> Look GC. Murphy MM. Campbell DA. Gallop MA. Tetrahedron Lett. 1995, 36: 2937

<A NAME="RZ20105SS-4D">4d</A> Vaas RS. Dudas J. Varma RS. Tetrahedron Lett. 1999, 40: 4951

ZnCl₂:

<A NAME="RZ20105SS-4E">4e</A> Billman JH. Tai KM. J. Org. Chem. 1958, 23: 535

Ti(IV):

<A NAME="RZ20105SS-4F">4f</A> White WA. Weingarten H. J. Org. Chem. 1967, 32: 213

<A NAME="RZ20105SS-4G">4g</A> Moretti I. Torre G. Synthesis 1970, 141

<A NAME="RZ20105SS-4H">4h</A> Jennings WB. Lovely CJ. Tetrahedron Lett. 1988, 29: 3725

<A NAME="RZ20105SS-4I">4i</A> Armstrong JD. Wolfe CN. Keller JL. Linch J. Bhupathy M. Volante RP. de Vita RJ. Tetrahedron Lett. 1997, 38: 1531

MgSO₄:

<A NAME="RZ20105SS-4J">4j</A> Branchaud BP. J. Org. Chem. 1983, 48: 3531

MgClO₄:

<A NAME="RZ20105SS-4K">4k</A> Chakraboti AK. Bhagat S. Rudrawar S. Tetrahedron Lett. 2004, 45: 7641

Al₂O₃:

<A NAME="RZ20105SS-4L">4l</A> Texier-Bullet F. Synthesis 1986, 679

Clay:

<A NAME="RZ20105SS-4M">4m</A> Varma RS. Dahiya R. Kumar S. Tetrahedron Lett. 1997, 38: 2039

CuSO₄:

<A NAME="RZ20105SS-4N">4n</A> Liu G. Cogan DA. Owens TD. Tang TP. Ellman JA. J. Org. Chem. 1999, 64: 1278

Ionic liquid:

<A NAME="RZ20105SS-4O">4o</A> Andrade CKZ. Takada SCS. Alves LM. Rodrigues JP. Suarez PAZ. Brandão RF. Soares VCD. Synlett 2004, 2135

Enaminone syntheses using different catalysts. Al₂O₃:

<A NAME="RZ20105SS-5A">5a</A> Valduga CL. Braibante HS. Braibante MEF. J. Heterocycl. Chem. 1998, 35: 189

SiO₂ under microwave irradiation:

<A NAME="RZ20105SS-5B">5b</A> Rechsteimer B. Texier-Bullet F. Hamelin J. Tetrahedron Lett. 1993, 34: 5071

Clay:

<A NAME="RZ20105SS-5C">5c</A> Braibante MEF. Braibante HS. Missio L. Andricopulo A. Synthesis 1994, 898

NaAuCl₄:

<A NAME="RZ20105SS-5D">5d</A> Arcadi A. Bianchi G. Di Giuseppe S. Marinelli F. Green Chem. 2003, 5: 64

Amine in water:

<A NAME="RZ20105SS-5E">5e</A> Stefani HA. Costa IM. de O Silva D. Synthesis 2000, 1526

Ultrasound:

<A NAME="RZ20105SS-5F">5f</A> Brandt CA. da Silva ACMP. Pancote CG. Brito CH. da Silveira MAB. Synthesis 2004, 1557

Zn(ClO₄)₂:

<A NAME="RZ20105SS-5G">5g</A> Bartoli G. Bosco M. Locatelli M. Marcantoni E. Melchiorre P. Sambri L. Synlett 2004, 239

CeCl₃:

<A NAME="RZ20105SS-5H">5h</A> Khodaei MM. Khosropour AR. Kookhazadeh M. Synlett 2004, 1980

<A NAME="RZ20105SS-6A">6a</A> Kobayashi S. Sugiura M. Kitagawa H. Lam WW.-L. Chem. Rev. 2002, 102: 2227

<A NAME="RZ20105SS-6B">6b</A> Kobayashi S. Menabe K. Acc. Chem. Res. 2002, 35: 209

<A NAME="RZ20105SS-6C">6c</A> Kobayashi S. Nagayama S. Busujima T. J. Am. Chem. Soc. 1998, 120: 8287

<A NAME="RZ20105SS-7A">7a</A> Tsuruta H. Yamaguchi K. Imamoto T. Tetrahedron 2003, 59: 10419

<A NAME="RZ20105SS-7B">7b</A> Tsuruta H. Yamaguchi K. Imamoto T. Chem. Commun. 1999, 1703

<A NAME="RZ20105SS-8A">8a</A> Firouzabadi H. Iranpoor N. Sobhani S. Synthesis 2004, 2692

<A NAME="RZ20105SS-8B">8b</A> Aspinall HC. Bissett JS. Greeves N. Levin D. Tetrahedron Lett. 2002, 43: 323

<A NAME="RZ20105SS-9A">9a</A> Procopio A. Dalpozzo R. De Nino A. Maiuolo L. Russo B. Sindona G. Adv. Synth. Catal. 2004, 346: 1465

<A NAME="RZ20105SS-9B">9b</A> Dalpozzo R. De Nino A. Maiuolo L. Nardi M. Procopio A. Tagarelli A. Synthesis 2004, 496

<A NAME="RZ20105SS-9C">9c</A> Procopio A. Dalpozzo R. De Nino A. Nardi M. Sindona G. Tagarelli A. Synlett 2004, 2633

<A NAME="RZ20105SS-9D">9d</A> Procopio A. Dalpozzo R. De Nino A. Maiuolo L. Nardi M. Russo B. Adv. Synth. Catal. 2005, 347: 1447

<A NAME="RZ20105SS-9E">9e</A> Procopio A. Dalpozzo R. De Nino A. Maiuolo L. Nardi M. Romeo G. Org. Biomol. Chem. 2005, 4129

<A NAME="RZ20105SS-9F">9f</A> Procopio A. Dalpozzo R. De Nino A. Nardi M. Russo B. Tagarelli A. Synthesis 2006, 332

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.

<A NAME="RZ20105SS-11">11</A> Layer RW. Chem. Rev. 1963, 63: 489

<A NAME="RZ20105SS-12">12</A> Bartoli G. Bartolacci M. Giuliani A. Marcantoni E. Massaccesi M. Torreggiani E. J. Org. Chem. 2005, 70: 169

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.

LD₅₀ of erbium salts is 4417 mg/Kg against 4000 mg/Kg for NaCl.

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.

<A NAME="RZ20105SS-16">16</A> Bull SD. Davies SG. Fenton G. Mulvaney AW. Prasad RS. Smith AD. J. Chem. Soc., Perkin Trans. 1 2000, 3765

<A NAME="RZ20105SS-17">17</A> Nongkunsarn P. Ramsden CA. Tetrahedron 1997, 53: 3805

<A NAME="RZ20105SS-18">18</A> Forlani L. Sintoni M. Todesco PE. Gazz. Chim. Ital. 1986, 116: 229

<A NAME="RZ20105SS-19">19</A> Egger H. Djerassi CJ. J. Am. Chem. Soc. 1973, 95: 3710

<A NAME="RZ20105SS-20">20</A> Johansson A. Abrahamsson P. Davidsson O. Tetrahedron: Asymmetry 2003, 14: 1261

<A NAME="RZ20105SS-21">21</A> Yoon NM. Kim EG. Son HS. Choi J. Synth. Commun. 1993, 23: 1595

<A NAME="RZ20105SS-22">22</A> Sassaman MB. Tetrahedron 1996, 52: 10835

<A NAME="RZ20105SS-23">23</A> Jones D. Roberts A. Cavell K. Keim W. Englert U. Kelton BW. White AH. J. Chem. Soc., Dalton Trans. 1998, 255

<A NAME="RZ20105SS-24">24</A> Dudek GO. Holm RH. J. Am. Chem. Soc. 1962, 84: 2691

<A NAME="RZ20105SS-25">25</A> Bartoli G. Cimarelli C. Palmieri G. Bosco M. Dalpozzo R. Synthesis 1990, 895

<A NAME="RZ20105SS-26">26</A> Kashima C. Aoyama H. Yamamoto Y. Nishio T. Yamada K. J. Chem. Soc., Perkin Trans. 2 1975, 665

<A NAME="RZ20105SS-27">27</A> Boatman S. Hauser CR. J. Org. Chem. 1966, 31: 1785

<A NAME="RZ20105SS-28">28</A> Bartoli G. Cimarelli C. Dalpozzo R. Palmieri G. Tetrahedron 1995, 51: 8613