Chloromethyl 4-Pentenyl Ether

[98486-13-6]  · C6H11ClO  · Chloromethyl 4-Pentenyl Ether  · (MW 134.61)

(protection of alcohols1)

Alternate Name: 4-pentenyloxymethyl chloride; POMCl.

Physical Data: bp 158-160 °C/760 mmHg, 34-38 °C/3.1 mmHg.

Solubility: sol dichloromethane.

Preparative Method: chloromethyl 4-pentenyl ether is prepared in 90-98% yield by treatment of a mixture of 4-pentenol and Paraformaldehyde (1.25 equiv) with Hydrogen Chloride gas at 0 °C. The crude product can be used directly or purified by distillation.2,3

Purification: by distillation.

Handling, Storage, and Precautions: potent alkylating agent; moisture sensitive. Use in a fume hood.

Protection of Alcohols.

Primary or secondary alcohols can be protected with the POM group upon treatment with POMCl (2 equiv) in the presence of Hünig's base (Diisopropylethylamine) (4 equiv) in dichloromethane (eq 1).2 This protective group survives in 75% aqueous acetic acid but not in 5% aqueous hydrochloric acid.4 Deprotection is performed with N-Bromosuccinimide (2.5 equiv) in 1% aqueous acetonitrile or a 1:1 mixture of 2% aqueous acetonitrile and dichloromethane.4 The mild deprotection processes can tolerate many other protecting groups such as t-butyldimethylsilyl, benzyl, p-methoxybenzyl, acyl, allyl, and ethoxyethyl groups.5

1. Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.; Wiley: New York, 1991; p 26.
2. Fraser-Reid, B.; Udodong, U. E.; Wu, Z.; Ottosson, H.; Merritt, J. R.; Rao, C. S.; Roberts, C.; Madsen, R. SL 1992, 927.
3. Colonge, J.; Boisde, P. BSF 1956, 23, 824.
4. Wu, Z.; Mootoo, D. R.; Fraser-Reid, B. TL 1988, 29, 6549.
5. Mootoo, D. R.; Date, V.; Fraser-Reid, B. JACS 1988, 110, 2662.

Yeun-Min Tsai

National Taiwan University, Taipei, Republic of China

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