144136-74-3Relevant articles and documents
Allylmetallation of 1-Silylalkynes by 2-(Bromozincmethyl)-2-alkenyl Ethers followed by Pd(0)-catalyzed Cyclization: A one-pot Synthesis of 4-Methylenecyclopentenes
Louw, Jaap van der,Baan, Juul L. van der,Kanter, Franciscus J. J. de,Bickelhaupt, Friedrich,Klumpp, Gerhard W.
, p. 6087 - 6104 (2007/10/02)
Reaction of 2-(bromozincmethyl)-2-alkenyl ethers 1 a,b,c,d with 1-(trimethylsilyl)-1-alkynes 2 afforded carbometallation products 3, which were converted by Pd(0)-catalyzed cyclization to 4-methylenecyclopentenes 5.The rates of both the addition and cyclization step depend on the concentration of the organozinc compound and the preparation of 5 is best performed using a 1,4-1,8 M solution of 1.At lower concentrations reaction times must be longer and, when 1c is reacted, the addition reaction is incomplete and gives rise to a mixture of products (3 and 14), which on Pd(0)-treatment leads to a mixture of isomeric methylenecyclopentenes (5, 15 and 16). - Key Words: alkyne addition; carbometallation; 2-alkenylzinc compounds; Pd(0)-catalysis; cyclopentenes.