Negishi, Eiichi published the artcileMetal promoted cyclization. 18. Novel cycloalkylation reactions of (ω-halo-1-alkenyl)metal derivatives. Synthetic scope and mechanism, SDS of cas: 69361-41-7, the publication is Journal of the American Chemical Society (1988), 110(16), 5383-96, database is CAplus.
(ω-Haloalkenyl)metals undergo both σ- and π-type cyclization reactions. The σ-cycloalkylation reaction, which has so far been observed only with alkenyllithiums, provides 3- through 7-membered rings in high yields. It requires the cis relationship between Li and the ω-haloalkyl group in the cyclization step. The presence of a trialkylsilyl group on the Li-bearing C atom facilitates configurational isomerization. However, it is not necessary for cyclization. The reaction proceeds with retention of regiochem. The cycloalkylation reactions of (ω-halo-1-silyl-1-alkenyl)metals containing Al, Zn, Zr, or Si, on the other hand, proceed via π-type cyclization processes. Thus, cyclization of X(CH2)2CMe:C(SiMe3)(AlMe2), prepared by the reaction of X(CH2)2CCSiMe3 (X = Cl, Br, iodo, 4-MeC6H4SO2) with Me3Al in presence of (η5-C5H5)2ZrCl2 in CH2Cl2, gave 2-methyl-1-(trimethylsilyl)cyclobutene. The relative ease of ring formation with respect to ring size is 3 and 4 ≫ 5 < 6. Formation of cyclobutenylsilanes is nonregiospecific. The stereochem. of alkenylmetal intermediates is unimportant, but the presence of a silyl group as the second metal group is necessary. The reaction can be inhibited by some polar solvents, such as THF. All of these facts can be accommodated by π-cyclization mechanisms and Baldwin’s cyclization rules.
Journal of the American Chemical Society published new progress about 69361-41-7. 69361-41-7 belongs to bromides-buliding-blocks, auxiliary class PROTAC Linker,Aliphatic Linker, name is (4-Bromobut-1-yn-1-yl)trimethylsilane, and the molecular formula is C7H13BrSi, SDS of cas: 69361-41-7.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary