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Stereoselective transformation of Baylis-Hillman acetates 1 into corresponding (Z)-allyl iodides 2 has been achieved by treatment of 1 with samarium triiodide in THF. Remarkable rate acceleration of samarium triiodide-mediated iodination of 1 was found when ionic liquid 1-n-butyl-3-methyl-imidazolium tetrafluroborate ([bmim]BF4) was used as reaction media in stead of THF. This novel approach proceeds readily at 50 °C within a few minutes to afford (Z)-allyl iodides 2 in excellent yields. A mechanism involving stereoselective iodination of the acetates of Baylis-Hillman adducts by samarium triiodide is described, in which a six-membered ring transition state played a key role in the stereoselective formation of 2.
Stereoselective transformation of Baylis-Hillman acetates 1 into corresponding (Z) -allyl iodides 2 has been achieved by treatment of 1 with samarium triiodide in THF. Remarkable rate of acceleration of samarium triiodide-mediated iodination of 1 was found when ionic liquid 1-n- butyl-3-methyl-imidazolium tetrafluroborate ([bmim] BF4) was used as reaction media in stead of THF. This novel approach facilitates at 50 ° C within a few minutes to afford (Z) -allyl iodides 2 in excellent yields. A mechanism involved stereoselective iodination of the acetates of Baylis-Hillman adducts by samarium triiodide is described, in which a six-membered ring transition state played a key role in the stereoselective formation of 2.