Novel Regio- and stereoselective olefin syntheses: hydride abstraction from organoiron compounds

Abstract

Received S e p t e m b e r 5, 1979Treatment of the compounds ~6-C5H5Fe(C0)2CHR1CH~R* (R = H, alkyl, aryl) with Ph3CfBF4-results in abstraction of a 8-hydrogen atom to give triphenylmethane and the cationic olefin complexes, [ T~-C~H~F~-(C0)2(CHR1CHR2)]+BF4-; liberation of the olefins can be effected by treatment with sodium iodide in acetone. The reactions have synthetic utility because (a) 1-and 2-alkyliron compounds generally give only the terminal olefin and (b) 3-alkyliron compounds give only (2)-2-olefins. The thermodynamically more stable E internal olefins are not formed. Optimum reaction conditions and compatibility of various functional groups with the reaction conditions are also discussed,

Transition metal-alkenyl complexes [M–(CH2)nCHCH2, n≥2]: Synthesis, structure, reactivity and applications

“…In some of these cases, the C C double bond undergoes an addition reaction to yield a functionalized metalalkyl complex. Similar to metal alkyls, the reactivity with the trityl salt Ph 3 CBF 4 has been reported by Baird and co-workers to cause ␤-hydride elimination giving rise a new metal-olefin bond [14]. Details of these various reaction pathways are shown in Scheme 9.…”

“…The first report of the synthesis of a metal-alkenyl complex we found in the literature was that of the iron-butenyl complex, CpFe(CO) 2 (CH 2 CH 2 CH CH 2 ) (7), by Green and Smith [13] which was later also reported by others [14,15] The synthesis of a series of these iron-alkenyl complexes, using the anion method, was reported by Roustan et al [32] who also reported on the reactivity of the complexes. Iron-alkenyl complexes of this type have also been investigated by Mapolie and co-workers who prepared a series of these complexes with varying alkenyl chain lengths, as well as the analogous pentamethylcyclopentadienyl complexes, viz.…”

“…Thus far, the most frequently reported metal-alkenyl complexes are those containing the metals such as Fe [13][14][15][16][17]32,33], Pt [18][19][20] and Ti [21][22][23][24], with only a few reports of complexes based on other metals such as Ni [25], Hf [26], Rh [27], Mo [28,29], Co [30,31], Pd [34], Ru [35] and Zr [36] (Scheme 2 ). The main methods used for the synthesis of these complexes are (i) the anion route, (ii) the Grignard route, with only a few reports on synthesis, (iii) from dienes and (iv) by oxidative addition of a haloalkene to a transition metal.…”

“…The molybdenum-butenyl complex [CpMo(NO)(CO) (GePh 3 ){(CH 2 ) 2 CH CH 2 }] (14) was prepared by the reaction of [CpMo(NO)(CO)(GePh 3 )] − with 4-iodo-1-alkene and obtained in good yield [28].…”

“…The reactivity of the iron-alkenyl complexes has been investigated in detail including hydrogenation and hydroformylation reactions as well as the reaction with the Lewis acid TiCl 4 [13,14,16,17]. In some of these cases, the C C double bond undergoes an addition reaction to yield a functionalized metalalkyl complex.…”