Polymer-Supported β-Amino Thioesters as Catalysts for the Enantioselective Addition of Diethylzinc to Aldehydes

Heidi S. Eriksen; Sandra Cotes Oyaga; David C. Sherrington; Colin L. Gibson

doi:10.1055/s-2005-865238

LETTER

Polymer-Supported β-Amino Thioesters as Catalysts for the Enantioselective Addition of Diethylzinc to Aldehydes

Heidi S. Eriksen, Sandra Cotes Oyaga, David C. Sherrington, Colin L. Gibson*
Department of Pure & Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK
Fax: +44(141)5484246; e-Mail: c.l.gibson@strath.ac.uk;

Abstract

All articles of this category

Abstract

A series of novel polymer-supported thioesters were prepared and found to be effective catalysts for the enantioselective addition of diethylzinc to benzaldehyde. These catalysts gave 1-phenylpropanol in up to 86% ee. The catalysts were fully recyclable and could be used in subsequent additions with retention of the enantioselectivity and efficiency levels.

Key words

asymmetric catalysis - ligands - nucleophilic additions - polymers - supported catalysis

Full Text

References

Present address: Departamento de Química y Biología, Universidad del Norte, Km 5 via Puerto Colombia, Barranquilla, Colombia.

<A NAME="RD04005ST-2">2</A> For reviews see: Pu L. Hong-Bin Y. Chem. Rev. 2001, 101: 757

For reviews of soluble enantioselective catalysts see:

<A NAME="RD04005ST-3A">3a</A> Soai K. Shibata T. In Comprehensive Asymmetric Catalysis Vol. 2: Jacobsen EN. Pfalz A. Yamamoto H. Springer-Verlag; Berlin: 1999. p.911-922

<A NAME="RD04005ST-3B">3b</A> Noyori R. In Asymmetric Catalysis in Organic Synthesis Wiley; New York: 1994. p.260-278

<A NAME="RD04005ST-3C">3c</A> Soai K. Niwa S. Chem. Rev. 1992, 92: 833

<A NAME="RD04005ST-3D">3d</A> Noyori R. Kitamura M. Angew. Chem., Int. Ed. Engl. 1991, 30: 46

For reviews of polymer-supported catalysts see:

<A NAME="RD04005ST-4A">4a</A> Fan Q.-H. Li Y.-M. Chan ASC. Chem. Rev. 2002, 102: 3385

<A NAME="RD04005ST-4B">4b</A> de Miguel YR. Brulé E. Margue RG. J. Chem. Soc., Perkin Trans. 1 2001, 3085

<A NAME="RD04005ST-4C">4c</A> Clapham B. Reger TS. Janda KD. Tetrahedron 2001, 57: 4637

<A NAME="RD04005ST-5A">5a</A> Hof RP. Poelert MA. Peper NCMW. Kellogg RM. Tetrahedron: Asymmetry 1994, 5: 31

<A NAME="RD04005ST-5B">5b</A> Fitzpatrick K. Hulst R. Kellogg RM. Tetrahedron: Asymmetry 1995, 6: 1861

<A NAME="RD04005ST-5C">5c</A> Kang J. Lee DJW. Kim JI. Chem. Commun. 1994, 2009

<A NAME="RD04005ST-5D">5d</A> Kang J. Kim DS. Kim JI. Synlett 1994, 842

<A NAME="RD04005ST-5E">5e</A> Masaki Y. Satoh Y. Makihara T. Shi M. Chem. Pharm. Bull. 1996, 44: 454

<A NAME="RD04005ST-5F">5f</A> Gibson CL. Chem. Commun. 1996, 645

<A NAME="RD04005ST-5G">5g</A> Kang J. Kim JB. Kim JW. Lee D. J. Chem Soc., Perkin Trans. 2 1997, 189

<A NAME="RD04005ST-5H">5h</A> Nakano H. Kumagai N. Matsuzaki H. Kabuto C. Hongo H. Tetrahedron: Asymmetry 1997, 8: 1391

<A NAME="RD04005ST-5I">5i</A> Iwasa K. Hongo H. Heterocycles 1997, 46: 267

<A NAME="RD04005ST-5J">5j</A> Chelucci G. Berta D. Fabbri D. Pinna GA. Saba A. Ulgheri F. Tetrahedron: Asymmetry 1998, 9: 1933

<A NAME="RD04005ST-5K">5k</A> Aurich HG. Soeberdt M. Tetrahedron Lett. 1998, 39: 2553

<A NAME="RD04005ST-5L">5l</A> Kossenjans M. Soebert M. Wallbaum S. Harms K. Martens J. Aurich HG. J. Chem Soc., Perkin Trans. 1 1999, 2353

<A NAME="RD04005ST-5M">5m</A> Tseng S.-L. Yang T.-K. Tetrahedron: Asymmetry 2004, 15: 3375

For recent examples of b-amino sulfur ligands as catalysts in the diethylzinc addition to aldehydes see:

<A NAME="RD04005ST-6A">6a</A> Braga AL. Milani P. Paixão MW. Zeni G. Rodrigues OED. Alves EF. Chem. Commun. 2004, 2488

<A NAME="RD04005ST-6B">6b</A> Braga AL. Vargas F. Silveira CC. de Andrade LH. Tetrahedron Lett. 2002, 43: 2335

<A NAME="RD04005ST-6C">6c</A> Braga AL. Appelt HR. Schneider PH. Rodrigues OED. Silveira CC. Wessjohann LA. Tetrahedron 2001, 57: 3291

<A NAME="RD04005ST-6D">6d</A> Jimeno C. Moyano A. Pericàs MA. Riera A. Synlett 2001, 1152

<A NAME="RD04005ST-7">7</A> For examples of the lower catalytic effectiveness of β-amino thioethers over the corresponding disulfides see: Braga AL. Appelt HR. Schneider PH. Silveira CC. Wessjohann LA. Tetrahedron: Asymmetry 1999, 10: 1733

<A NAME="RD04005ST-8A">8a</A> In related amino aryl diselenides, Wirth et al. have unequivocally established that an ethyl selenide (45% yield) is obtained upon treatment with diethylzinc. This ethyl selenide was proven not to be the dominant catalytically active species in the addition of diethylzinc to benzaldehyde (17% yield). Furthermore, these workers also provided NMR evidence for zinc selenolate dimers. See: Wirth T. Kulicke KJ. Fragale G. Helv. Chim. Acta 1996, 79: 1957

<A NAME="RD04005ST-8B">8b</A> A similar observation has been made that selenoethers derived from aliphatic amino diselenides are not catalytically productive: Braga AL. Paixão MW. Lüdtke DS. Silveira CC. Rodrigues OED. Org. Lett. 2003, 5: 2635

<A NAME="RD04005ST-9">9</A> Gibson CL. Tetrahedron: Asymmetry 1999, 10: 1551

<A NAME="RD04005ST-10">10</A> Kleijn H. Rijnberg E. Jastrzebski JTBH. van Koten G. Org. Lett. 1999, 1: 853

<A NAME="RD04005ST-11">11</A> Lui G. Ellman JA. J. Org. Chem. 1995, 60: 7712

<A NAME="RD04005ST-12">12</A> Hanessian S. Xie F. Tetrahedron Lett. 1998, 39: 733

<A NAME="RD04005ST-13">13</A> Hanessian S. Huynh HK. Tetrahedron Lett. 1999, 40: 671

<A NAME="RD04005ST-14">14</A> Lecavalier P. Bald E. Jiang Y. Fréchet JMJ. Reactive Polymers 1985, 3: 315

Typical Procedure for the Synthesis of the Polymer-Supported Thioesters 6 and 7.
To a stirred solution of [(2S)-1-(polystyrylmethyl)pyrrol-idinyl]methanol (0.5008 g) and triphenylphosphine (0.5885 g) in anhyd toluene (10 mL) under nitrogen was added at r.t. a solution of DEAD (0.3912 g) in toluene (1 mL). After 3-5 min thiobenzoic acid (0.3012 g) in toluene (1 mL) was added. The resulting mixture was stirred for a further 45 h at r.t. At the completion of this period the polymer was filtered and rinsed with toluene, DMF and EtOH. The polymer beads were then transferred to a soxhlet apparatus and washed with THF for 1 d, rinsed with acetone and finally soxhlet extracted with Et₂O for 1 d. The beads were then dried in a drying pistol (40 °C, 0.05 mmHg) for 24 h to give 0.5639 g of polymer. IR (KBr): ν_max = 1664 cm^-1. Anal. Calcd: N, 2.08; S, 4.78. Found: N, 1.94; S, 3.82. Loading 1.19 mmol S/g and an 80% conversion based on sulfur microanalysis.

<A NAME="RD04005ST-16">16</A> Yelm KE. Tetrahedron Lett. 1999, 40: 1101

<A NAME="RD04005ST-17">17</A> Govindachari TR. Rajagopalan TG. Viswanathan N. J. Chem. Soc., Perkin Trans. 1 1974, 1161

Typical Procedure for the Enantioselective Addition of Diethylzinc to Benzaldehyde Catalysed by Polymer-Supported Catalysts 6-8.
Diethylzinc (1.87 mL of a 1 M solution in hexane, 1.87 mmol) was added to a stirred solution of the catalyst (0.024 mmol, 0.048 mmol, or 0.096 mmol based on sulfur content) in anhyd toluene (5 mL) under a nitrogen atmosphere. After stirring at r.t. for 2 h the solution was cooled to -27 °C whereupon, freshly distilled benzaldehyde (0.937 mmol) was added and the resulting solution was stirred at 0 °C. After stirring for 19 h at this temperature additional diethylzinc was added (1.87 mL, 1.87 mmol) and the mixture stirred for a further 46 h at 0 °C. At the completion of this period there was no starting aldehyde, so HCl was added (1 M, 3 mL). The aqueous phase was extracted with CH₂Cl₂ (3 × 10 mL) and dried over Na₂SO₄. Evaporation of the solvent and silica column chromatography (hexane-EtOAc, 88:12) afforded (R)-(+)-1-phenyl-1-propanol as a colourless oil. ¹H NMR (CDCl₃): δ = 0.9 (t, 3 H, CH₂CH ₃, J = 7.4 Hz), 1.65-2.00 (m, 3 H, CH ₂CH₃, J = 7.4 Hz, OH), 4.60 (t, 1 H, CHOH, J = 6.6 Hz), 7.30-7.40 (m, 5 H, ArCH). The ee was determined by HPLC using a DAICEL chiralcel OB column with 3% i-PrOH in hexane (flowrate: 0.5 mL/min); t _R = 25 min for the S-isomer and 31 min for the R-isomer.

<A NAME="RD04005ST-19">19</A> Itsuno S. Fréchet JMJ. J. Org. Chem. 1987, 52: 4140

<A NAME="RD04005ST-20">20</A> Sung DW. Hodge P. Stratford PW. J. Chem. Soc., Perkin Trans. 1 1999, 1463