Synlett 2004(7): 1276-1278  
DOI: 10.1055/s-2004-825602
LETTER
© Georg Thieme Verlag Stuttgart · New York

Bismuth(III) Chloride Catalyzed Efficient and Selective Cleavage of Trityl Ethers [1]

Gowravaram Sabitha*, E. Venkata Reddy, R. Swapna, N. Mallikarjun Reddy, J. S. Yadav
Organic Division I, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax: +91(40)27160512; e-Mail: sabitha@iict.ap.nic.in;
Further Information

Publication History

Received 14 October 2003
Publication Date:
19 May 2004 (online)

Abstract

A highly selective and efficient protocol has been developed for detritylation using 5 mol% BiCl3 in acetonitrile. The ­cleavage proceeds at room temperature in high yields and the conditions are mild enough to tolerate a variety of acid-base sensitive functional groups.

1

IICT Communication No. 031004.

1

IICT Communication No. 031004.

17

General Procedure. Trityl ether (2 mmol) in dry MeCN (2 mL), was treated with a catalytic amount of BiCl3 (5 mol%) and stirred at r.t. After complete conversion of the reaction as indicated by TLC, the reaction mixture was filtered through a small pad of Celite. The filtrate was extracted with EtOAc, washed with brine and dried over anhyd Na2SO4. After evaporation, the residue was purified by column chromatography using silica gel (60-120 mesh; hexane-EtOAc) to furnish pure alcohol.
Spectroscopic data for selected compounds. Compound 1a: IR (neat): 2941, 1057, 749 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.92-2.12 (m, 2 H), 2.72 (t, 2 H, J = 10.0 Hz), 3.17 (t, 2 H, J = 5.1 Hz), 7.12-7.35 (m, 15 H), 7.47 (d, 6 H, J = 8.2 Hz). MS: m/z = 378 [M+]. Compound 2a: IR (neat): 3355, 2943, 1057, 745 cm-1. 1H NMR (300 MHz, CDCl3): δ = 1.92-2.12 (m, 2 H), 2.72 (t, 2 H, J = 5.2 Hz), 3.63 (t, 2 H, J = 9.8 Hz), 7.15-7.25 (m, 5 H). MS: m/z = 136 [M+]. Compound 1d: IR (neat): 2358, 1219, 1109, 773 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.03 (s, 9 H), 1.38 (s, 2 H), 1.51-1.62 (m, 4 H), 3.02 (t, 2 H, J = 5.9 Hz), 3.62 (t, 3 H, J = 5.2 Hz), 7.16-7.41 (m, 19 H), 7.39 (d, 6 H, J = 7.9 Hz). MS: m/z = 585 [M+]. Compound 2d: IR (neat): 3332, 2855, 1104, 1028, 772 cm-1. 1H NMR (300 MHz, CDCl3): δ = 1.03 (s, 9 H), 1.39-1.59 (m, 6 H), 3.59 (t, 2 H, J = 6.0 Hz), 3.64 (t, 2 H, J = 6.0 Hz), 7.33-7.38 (m, 2 H), 7.62 (d, 2 H, J = 7.3 Hz). MS: m/z = 342 [M+]. Compound 1e: IR (neat): 2936, 1727, 1156, 1071 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.19 (s, 9 H), 1.46-1.71 (m, 6 H), 3.06 (t, 2 H, J = 5.9 Hz), 4.03 (t, 2 H, J = 5.9 Hz), 7.18-7.33 (m, 9 H), 7.45 (d, 6 H, J = 8.2 Hz). MS: m/z = 430 [M+]. Compound 2e: IR (neat): 3439, 2938, 1728, 1159, 1057 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.18 (s, 9 H), 1.38-1.72 (m, 6 H), 3.62 (t, 2 H, J = 6.6 Hz), 4.04 (t, 2 H, J = 6.6 Hz). MS: m/z = 188 [M+]. Compound 1i: IR (neat): 2361, 1219, 1174, 1060, 771 cm- 1. 1H NMR (200 MHz, CDCl3): δ = 3.60 (d, 2 H, J = 6.6 Hz), 3.80 (s, 3 H), 3.85 (d, 2 H, J = 6.5 Hz), 4.30 (s, 2 H), 5.60-5.90 (m, 2 H), 6.76 (d, 2 H, J = 8.2 Hz), 7.15 (d, 2 H, J = 8.1 Hz), 7.30 (m, 9 H), 7.45 (d, 6 H, J = 8.2 Hz). MS: m/z = 450 [M+]. Compound 2i: IR (neat): 3418, 2935, 1514, 1174, 1032 cm-1. 1H NMR (200 MHz, CDCl3): δ = 3.80 (s, 3 H), 4.01 (d, 2 H, J = 6.5 Hz), 4.15 (d, 2 H, J = 6.5 Hz), 4.40 (s, 2 H), 5.50-5.90 (m, 2 H), 6.85 (d, 2 H, J = 8.2 Hz), 7.27 (d, 2 H, J = 8.2 Hz). MS: m/z = 208 [M+]. Compound 1n: IR (neat): 2985, 2935, 1611, 1509, 1216, 1077 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.31 (s, 6 H), 1.45 (s, 3 H), 1.53 (s, 3 H), 3.50-3.63 (m, 2 H), 3.90 (dt, 1 H, J = 6.0 and 2.3 Hz), 4.20-4.30 (m, 2 H), 4.48-4.58 (m, 2 H), 5.50 (d, 1 H, J = 5.1 Hz), 7.20 (m, 9 H), 7.40 (d, 6 H, J = 7.3 Hz). MS: m/z = 503 [M+]. Compound 2n: IR (neat): 3425, 2980, 2930, 1509, 1077 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.31 (s, 6 H), 1.45 (s, 3 H), 1.53 (s, 3 H), 3.60-3.73 (m, 2 H), 3.80 (dt, 1 H, J = 6.0 and 2.3 Hz), 4.20-4.30 (m, 2 H), 4.48-4.58 (m, 2 H), 5.50 (d, 1 H, J = 5.1 Hz). MS: m/z = 260 [M+].