4894-63-7Relevant articles and documents
Evidence for a free radical mechanism in the decomposition of bis(but-2-enyl)tellurium
Stevenson, John,Bell, William,Ferry, Joseph,Cole-Hamilton, David J.,Hails, Janet E.
, p. 141 - 145 (2007/10/02)
Reactions of basic aqueous solution of Na2Te with MeCH=CHCH2Br or CH2=CHCHMeCl give ZZ-, ZE- and EE(MeCH=CHCH2)2.This is interpreted in terms of a mechanism involving attack of Na2Te on the 2-butenyl cation formed from the allyl halide under the basic reaction conditions.The rate of reaction to give the E-configuration is ca. 3 times that to form the Z.Decomposition of (MeCH=CHCH2)2Te in the liquid or gas phases gives all possible products arising from dimerization of the allyl group.This is interpreted in terms of homolytic fission of the Te-C bond followed by coupling of the allyl radicals formed, particularly as no compounds containing CH2-CHCHMeTe are recovered after partial pyrolysis.The products can be fitted to a purely statistical model in which the reactivity ratio of the primary to secondary allyl is ca. 0.63:0.37.The statistical fit is taken to indicate that mechanism other than that involving homolytic fission and free radical coupling play a negligible part.
Reaction Of Allylic Boron and Aluminium "Ate" Complexes with Organic Halides and Carbonyl Compounds. Trialkylboranes as Regio-, Stereo-, and Chemoselective Control Elements
Yamamoto, Yoshinori,Yatagai, Hidetaka,Maruyama, Kazuhiro
, p. 1969 - 1975 (2007/10/02)
Lithium allylic boron ate complexes, prepared by the addition of trilakylboranes to an ether solution of allylic lithium compounds, regioselectively react with allylic halides to produce head-to-tail 1,5-dienes (eq 1).The ate complexes are also prepared from the reaction of allylic boranes with alkyllithium derivatives.Magnesium or copper allylic boron ate complexes are less effective.Lithium crotyl boron ate complexes undergo a rapid reaction with aldehydes with good threoselectivity (eq 2).The selectivity is affected by the steric hindrance of trialkylboranes, as explained by the steric parameters of the 6-membered transition state.The ate complexes react with α,β-unsaturated ketones in a competitive manner of 1,2 and 1,4 addition, while they add to cinnamaldehyde exclusively in a 1,2 manner.The chemoselective aspects are only investigated. 1H and 13 C NMR spectra of lithium allylic boron ate complexes clearly indicate (i) the prevention of allylic rearrangement, (ii) the predominant trans geometry of the crotyl unit in comparison with the corresponding trivalent crotylboron, and (iii) the relative importance of ?-? conjugation between the double bond and the carbon-boron bond (eq 3).
