Technical Note PS-

Resin-bound Phosphine

PS-Triphenylphosphine is a resin-bound Specifications equivalent of triphenylphosphine. The

Chemical Name: Diphenylphosphino-polystyrene capacity of the resin is determined by the

Resin Type: 1% Cross-linked poly(styrene-co- quantitation of benzyl bromide uptake in divinylbenzene) DMF (GC, internal standard method). P Loading: Typical loading 2.2 mmol/g, minimum loading 1.8 mmol/g (based on uptake of benzyl bromide) PS-Triphenylphosphine can be used in

Bead Size: 75–150 microns, 100–200 mesh Mitsunobu reactions to prepare aryl (95% within) ethers in good-to-excellent yields and in Application: Chlorination of acids and , high purities (Scheme 1).1 Wittig and Mitsunobu reactions, scavenging of alkyl halides

Typical Chlorination Conditions: 0.5 equivalent of acid or in CCl4, 3 h, reflux

Typical Mitsunobu Reaction Conditions: 1.0 1. MP-Carbonate (2.5 eq) equivalent of alcohol, 1.5 equivalent of phenol, X 2. Filter Alphatic or Aryl-OH X 2.2 equivalent of resin, and 1.6 equivalent of di- + PS-PPh3 + DBAD 3. TFA:DCM:H2O (50:48:2) HO 16 hr, RT, THF 4. LLE (extract into MTBE) Aryl or Aliphatic O tert-butyl azodicarboxylate (DBAD) at room tem- 2.2eq 1.6eq 5. Concentrate 1.5eq perature for 16 h

Typical Wittig Reaction Conditions: 2.0 equiv- Scheme 1. Mitsunobu reaction using PS-Triphenylphosphine alent of ylide resin, 8.0 equivalent of sodium bis (dimethylsilyl)/tetrahydrofuran Mitsunobu general procedure: Add a solution of the phenol to the PS- (NaHMDS/THF), resin washed with THF, followed by 1.0 equivalent of carbonyl compound in THF at Triphenylphosphine resin and allow the suspension to stand for 5 min. Add a room temperature for 16 h solution of DBAD (di-tert-butyl azodicarboxylate) and THF to this suspension and Typical Alkyl Halide Scavenging Conditions: agitate for 30 min at RT. Add a solution of the alcohol to this mixture and stir 3.0 equivalent of resin, DMF, 10 mL/g resin, the reaction overnight. To scavenge any excess phenols, add MP-Carbonate resin 20 OC, 16 h and stir for 2 h. Filter and wash with THF. Add TFA/DCM/water (50:48:2) to this solution and stir the mixture at RT for 2 h. Extract the product with MTBE, wash with water and concentrate the MTBE layer to obtain the product.

PS-Triphenylphosphine resin has also been used in the Wittig reaction to synthesize olefins conventionally2,3, and via microwave heating4 (Scheme 2). Microwave heating significantly enhances the reaction rate.

A. R1 PPh2 i. NaHMDS, THF, RT 1 R X PPh2 o 1 2 3 65 C, 16h R ii. R COR R R X 2 3 DMF

B. O O Ph K CO 2 3 O N H O P N + Br + Ph N N Cl O 150°C, 5 min Cl 1 MeOH

Scheme 2: Wittig reaction A: Traditional two step B: Microwave assisted one pot Wittig general procedure: Add the alkyl halide to a suspension of PS-Triphenylphosphine in DMF and stir the reaction mixture for 48 h at 65 ºC. Wash the resulting phosphonium resin with DMF, toluene, DCM, and diethyl ether and dry in vacuo for 12 h. Add THF to the dried phospho- nium resin in a reaction vessel, followed by the addition a solution of sodium bis(dimethylsi- lyl)amide in THF at room temperature and stir the reaction for 1 h. Wash the ylide resin with THF to remove excess base. Suspend the ylide resin in anhydrous THF, add a solution of the aldehyde in THF to this and stir for 16 h. Dilute the reaction mixture with hexanes and apply to a silica SPE cartridge followed by washing with hexane/ether (2:1). Concentrate the solvent to obtain the olefin.

PS-Triphenylphosphine can be used as a scavenger of alkyl halides. To scavenge alkyl halides stir the resin (3 equiv) with the alkyl halide in DMF (10mL/g of resin) at RT for 5-16 h or via microwave heating and filter.

The resin has also been used to convert alcohols and carboxylic acids to their corresponding chlorides using carbon tetrachloride5,6,7 or trichloroacetonitrile8 conventionally and via microwave heating (Scheme 3). www.biotage.com A. UNITED STATES AND CANADA Main Office: +1 434 979 2319 O PS-PPh (2.1 eq) Toll Free: +1 800 446 4752 OH 3 O Cl Fax: +1 434 979 4743 O O CCl4 Order Tel: +1 434 220 2687 1 equiv reflux, 3 h Order Fax: +1 434 296 8217

B. [email protected] O O N 1. PS-PPh3 (3 eq), CCl3CN (1.5 eq) OH 100 oC / 5 min N NOH UNITED KINGDOM BnO 2. DIEA (2 eq) BnO Main Office: +44 1443 811811 150 oC / 15 min NH2 Fax: +44 1443 816552 H3C Order Tel: +44 1443 811822 Order Fax: +44 1443 816816 Scheme 3. Chlorination of alcohols and acids using PS-Triphenylphosphine A: conventional B: [email protected] microwave-assisted

SWEDEN Chlorination general procedure: Add a solution of the alcohol or to a suspen- Main Office: +46 18 56 5900 Fax: +46 18 59 1922 sion of PS-Triphenylphosphine resin in CCl4 or trichloroacetonitrile and heat the reaction mixture Order Tel: +46 18 56 57 10 in an oil bath or in a microwave. Filter and concentrate filtrate to obtain the corresponding Order Fax: +46 18 56 57 05 chlorides. [email protected]

1. Tunoori, A. R.; Dutta, D.; Georg, G. I. Tetrahedron Lett. 1998, 39, 8951. GERMANY 2. Bernard, M.; Ford, W.T. J. Org. Chem. 1983, 48, 326. Tel: +49 7624 90 80 0 3. Bolli, M. H.; Ley, S.V. J. Chem. Soc., Perkin Trans. 1. 1998, 15, 2243. Fax: +49 7624 90 80 10 4. Westman, J. Org. Lett. 2001, 3(23), 3745-3747. [email protected] 5. Relles, H. M.; Schluenz, R.W. J. Am. Chem. Soc. 1974, 96, 6469. 6. Regen, S. L.; Lee, D. P. J. Org. Chem. 1975, 40, 1669. SWITZERLAND 7. Landi, J. J. Jr.; Brinkman, H. R. Synthesis 1992, 1093. Tel: +41 61 743 90 15 8. Wang, Y.; Miller, R.L.; Sauer, D. R. Djuric, S. W.; Org. Lett. 2005, 7(5), 925-928 Fax: +41 61 743 90 18 [email protected]

Ordering Information AUSTRIA Part Number Quantity Tel: +43 2231 63167 Fax: +43 2231 63520 800510 3 g [email protected] 800378 10 g 800379 25 g 800380 100 g JAPAN 800381 1000 g Tel: +81 422 28 1233 Fax: +81 422 28 1236 Copyright © 2007. All rights reserved. All brand and product names are trademarks or registered trademarks of [email protected] their respective companies. The information contained in this document is subject to change without notice.

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