Remarkable rate acceleration of SmI3-mediated iodination of acetates of Baylis-Hillman adducts in ionic liquid: facile synthesis of (Z)-allyl iodides.
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]BF(4)) was used as reaction media in stead of THF. This novel approach proceeds readily at 50 degrees 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.
Liu
Yun-kui
YK
State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, China.
Zheng
Hui
H
Xu
Dan-qian
DQ
Xu
Zhen-yuan
ZY
Zhang
Yong-min
YM
D000085:Acetates / Q000737:chemistry*; D007454:Iodides / Q000138:chemical synthesis*; D007477:Ions; D007700:Kinetics; D012493:Samarium / Q000737:chemistry*; D012996:Solutions
D000085:Acetates; D007454:Iodides; D007477:Ions; D012996:Solutions; D012493:Samarium