848074-59-9Relevant academic research and scientific papers
Carbocyclization reaction of ω-iodo- and 1,ω-diiodo-1-alkynes without the loss of iodine atoms through a carbenoid-chain process
Harada, Toshiro,Muramatsu, Keiko,Mizunashi, Kenia,Kitano, Chie,Imaoka, Daisuke,Fujiwara, Takayuki,Kataoka, Hiroshi
, p. 249 - 258 (2008/09/17)
(Chemical Equation Presented) Atom-economical carbocyclization reactions of ω-iodo-1-alkynes and 1,ω-diiodo-1-alkynes to give products with incorporation of iodine atoms is described. Cycloisomerization of 2-(2-propynyloxy)ethyl iodides is initiated by a catalytic amount of LDA to give 3-(iodomethylene)tetrahydrofurans in high yields. Upon treatment of with a catalytic amount of 1-hexynyllithium, 1ω-diiodo-1-alkynes efficiently undergo cycloisomerization to give (diiodomethylene)cycloalkanes. The diiodomethylene products are also obtained by iodine atom-transfer-type cyclization of ω-iodo-1-alkynes, using 1-iodo-1-hexyne as an external iodine atom source. Bromine atom-transfer and proton-transfer cyclization proceed as well by employing 1-bromo-1-octyne and 1-octyne, respectively. These reactions are proposed to proceed through a carbenoid-chain process involving exo-cyclization of the lithium acetylide intermediates to give Li,I-alkylidene carbenoids. It is shown that the exo-cyclization proceeded stereospecifically through inversion of the stereochemistry at the electrophilic carbon.
