Novel cyclization reaction of 1,ω-diiodo-1-alkynes without the loss of iodine atoms
作者:Toshiro Harada、Kenta Mizunashi、Keiko Muramatsu
DOI:10.1039/b516515f
日期:——
In the presence of 1-hexynyllithium (0.2â0.6 equiv.), 1,Ï-diiodo-1-alkynes undergo a new type of cyclization reaction without the loss of two iodine atoms to afford (diiodomethylene)cycloalkanes.
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
Alkylative Carbocyclization of ω-Iodoalkynyl Tosylates with Alkynyllithium Compounds Through a Carbenoid-Chain Process Leading to (1-Iodoprop-2-ynylidene)tetrahydrofurans and -cyclopropanes
carbocyclization reactions of ω‐iodoalkynyl tosylates with alkynyllithium compounds to give products with incorporated iodine atoms are described. Slow addition of 2‐(3‐iodoprop‐2‐ynyloxy)ethyl tosylates to 1‐alkynyllithium compounds in tetrahydrofuran at 40 °C followed by additional stirring at this temperature gives (Z)‐3‐(1‐iodoprop‐2‐ynylidene)tetrahydrofurans stereoselectively in good to moderate yields. Under