Allyl Chloroformate

[2937-50-0]  · C4H5ClO2  · Allyl Chloroformate  · (MW 120.54)

(preparation of allyl carbamates and allyl carbonates;1a may be used for preparation of a-allyl carbonyls and a,b-unsaturated carbonyls4)

Physical Data: bp 109-110 °C; d 1.136 g cm-3; fp 31 °C.

Solubility: sol most organic solvents.

Form Supplied in: clear, colorless liquid.

Handling, Storage, and Precautions: keep cold. Reacts with moist air. May contain small amounts of phosgene.

Protecting Group.

Allyl chloroformate has been used to prepare the allyl carbamate protecting groups for amines (eq 1)1 and the alkyl allyl carbonate group for protecting alcohols (eq 2).1a These blocking groups are useful because they are stable to acidic and some basic conditions but are easily removed under aprotic conditions with palladium or nickel catalysis in the presence of nucleophiles (eqs 3 and 4).1a,2

Preparation of a-Allyl and a,a-Diallyl Ketones.

Allyl enol carbonates formed from the reaction of enolates with allyl chloroformate rearrange in the presence of palladium(0) catalysts to provide a-allyl and a,a-diallyl ketones (eq 5).3

Preparation of Unsaturated Ketones, Aldehydes, and Nitriles.

Allyl enol carbonates and allyl esters provide good yields of a,b-unsaturated products when treated with palladium(II) and the appropriate ligand. The choice of ligand is critical to the optimal yield of either a-allylated product or unsaturated product (eq 6).4

1. (a) Corey, E. J.; Suggs, J. W. JOC 1973, 38, 3223. (b) Jeffery, P. D.; McCombie, S. W. JOC 1982, 47, 587. (c) Sennyey, G.; Barcelo, G.; Senset, J.-P. TL 1987, 28, 5809. (d) Hayakawa, Y.; Kato, H.; Uchiyama, M.; Kajino, H.; Noyori, R. JOC 1986, 51, 2400. (e) Kruse, C.; Holden, K. G. JOC 1985, 50, 2792. (f) Allainmat, M.; L'Haridon, P.; Toupet, L.; Plusquellec, D. S 1990, 27.
2. (a) Guibe, F.; Saint M'Leux, Y. TL 1981, 22, 3591. (b) Four, P.; Guibe, F. TL 1982, 23, 1825. (c) Kunz, H.; Unverzagt, C. AG(E) 1984, 23, 436. (d) Boullanger, P.; Descotes, G. TL 1985, 27, 2599. (e) Minami, I.; Ohasi, Y.; Shimizu, I.; Tsuji, J. TL 1985, 26, 2449. (f) Dangles, O.; Guibe, F.; Balavoine, G.; Lavielle, S.; Marquet, J. JOC 1987, 52, 4984. (g) Zahng, H. X.; Guibe, F.; Balavoine, G. TL 1988, 29, 623.
3. (a) Simizu, I.; Ohashi, Y.; Tsuji, J. TL 1983, 24, 3856. (b) Tsuji, J.; Minami, I.; Shimizu, I. TL 1983, 24, 1793. (c) Herrinton, P. M.; Klotz, K. L.; Hartley, W. M. JOC 1993, 58, 678.
4. (a) Minami, I.; Nisar, M.; Yuhara, M.; Shimizu, I.; Tsuji, J. S 1987, 992. (b) Shimiz, I.; Minami, I.; Tsuji, J. TL 1983, 24, 1797.

Paul M. Herrinton

The Upjohn Company, Kalamazoo, MI, USA

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