The preparation and variable temperature 1H NMR characterization of 1-(tri-n-butylstannyl)indene, 1-(Bu3Sn)C9H7

Morria, Robert J; Bock, Paul L.; Jefferis, Jesse M.; Goedde, Dean M.

doi:10.1016/s0277-5387(97)00161-7

Cited by 4 publications

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“…1 In a recent report the barrier for the sigmatropic migrations in 1a was determined to be approximately 20 kcal mol -1 . 3 indenyl derivatives of mercury, 7 silicon, 8 " 16 tin, 8,11,12,17 and germanium 8,12 followed this argumentation for the mechanism of sigmatropic migrations in 1b-e. Hydrogen sigmatropic shifts are observed in σ-indenyl derivatives 1 at elevated temperatures. 3 indenyl derivatives of mercury, 7 silicon, 8 " 16 tin, 8,11,12,17 and germanium 8,12 followed this argumentation for the mechanism of sigmatropic migrations in 1b-e. Hydrogen sigmatropic shifts are observed in σ-indenyl derivatives 1 at elevated temperatures.…”

Section: Introductionmentioning

confidence: 88%

Synthesis and Dynamic Behaviour of Diethyl(1-Indenyl)borane

Gridnev

Meller

1998

Main Group Metal Chemistry

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Sigmatropic [1,3] Β shift was observed by 2D 1 H EXSY NMR experiments in diethyl(1indenyl)borane 1i prepared in 83% yield from indenyl lithium and chlorodiethylborane. The activation barrier of the rearrangement (E A = 17.7±0.2 kcal mol -1 , InA = 28.6±0.5) was determined from a series of 2D 1 H EXSY spectra recorded in the temperature interval 25-80°C. After prolonged storage at ambient temperatures or short heating at 100°C an equilibrium between 1i, diethyl(3indenyl)borane 4i, and diethyl(2-indenyl)borane 5i is established (the equilibrium ratio 1i: 4i: 5i is 1 : 2.3 : 0.2). Addition of an excess of pentadeuteropyridiine leads to a new equilibrium between corresponding complexes (the ratio 1j: 4j: 5j is 1 : 3.2 : 0.2). CO CO X // la, 3a: X = (n-C5H5)Fe(CO)2 lb,3b:X = (C9H7)Hg lc, 3c: X = (CH3)3Si ld,3d:X = (CH3)3Ge le, 3e: X = (CH3)3Sn Scheme 1The much higher barrier for the rearrangement in 1a can be accounted for by the inevitable formation of an intermediate 3a. The latter is less stable than 1a due to loss of aromaticity. Since the alternative [1,3] mechanism of the sigmatropic migration in 1a does not require the formation of an unstable intermediate, it was concluded that the mechanism can be described by two consecutive [1,5] sigmatropic shifts (Scheme 1). 1 Later studies of the dynamic behaviour of σ-271 Brought to you by |

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