3975-81-3Relevant articles and documents
Photocycloaddition and ortho-hydrogen abstraction reactions of methyl arylglyoxylates: Structure dependent reactivities
Hu, Shengkui,Neckers, Douglas C.
, p. 1771 - 1778 (1999)
In photocycloaddition reactions between methyl arylglyoxylates and certain cyclo-1,3-dienes, the diastereochemical outcome of the photoproducts is shown to depend on the steric demand of the aryl group in the glyoxylate. Exclusive endo-aryloxetanes were p
2-(2,4-Di-tert-butylphenyl)-1,1-bis(trimethylsilyl)silene and 2-(2,4,6-Tri-tert-butylphenyl)-1,1-bis(trimethylslyl)silene - Two new sterically protected but still unstable silaethenes
Luderer, Frank,Retake, Helmut,Oehme, Harfmut
, p. 15 - 20 (2007/10/02)
(2,4-Di-terl-butylphenyl)tris(trimethylsilyl)silylmethanol (1a), prepared by the reaction of tris(trimethylsilyl)silylmagnesium bromide with 2,4-di-tert-butylbenzaldehyde, was deprotonated by treatment with methyllithium in ether at -78°C to give the transient 2-(2,4-di-tert-butylphenyi)-1,1-bis(trimethylsilyljsilene (3a), which dimerizes in a head-to-head fashion with the formation of (E)-/(Z)-3,4-bis(2,4-di-terf-butylphenyl)-1,1,2,2-tetrakis(trimethylsilyl)-l,2- disilacyclobutane (5). Besides 5 an unstable compound 4 was obtained, which was preliminarly assigned as 5,7-di-terf-butyl-l-(2,4-di-fert-butylphenyl)-1,2,3,8a-tetrahydro-2,2,3,3- tetrakis(trime thylsilyl)-1,2-disilanaphthalene (4), the formal [2 + 4] cyclodi-mer of 3a. Compound 4 gradually decomposes to give (E)-/(Z)-5, and is considered to be the kinetically preferred dirner of 3a, which is converted into the thermodynamically stable 5. 2,4,6-Tri-tert-butylbenzaldehyde reacts with tris(trimethylsilyljsilyllithium resulting in the formation of 6,8-ditert-butyl-l,2,3,4-tetrahydro-4,4-dimethyl-2,2-bis(trimethylsilyl)-2- silanaphthalene (6). Compound 6 is the product of the insertion of the Si=C bond into the C-H bond of an o-tertbutyl group of the intermediate 2-(2,4,6-tri-ferf-butylphenyl)l,l-bis{t.rimethylsilyl)silene (3b), which despite extreme steric shielding proved to be still unstable. For compounds (Z)-5 and 6 the results of the X-ray analyses are given.
Reactions of (2,4,6-Tri-t-butyl)thiobenzaldehyde with Diazo Compounds. Synthesis and Reactions of Sterically Congested Thiiranes
Watanabe, Soichiro,Kawashima, Takayuki,Tokitoh, Norihiro,Okazaki, Renji
, p. 1437 - 1448 (2007/10/02)
Sterically congested thiiranes having a 2,4,6-tri-t-butylphenyl group were synthesized by the reactions of (2,4,6-tri-t-butyl)thiobenzaldehyde with sterically hindered diazo compounds.Thermal desulfurization of the most congested thiirane, 2,2-di-t-butyl-3-(2,4,6-tri-t-butylphenyl)thiirane (15c), did not proceed even upon using highly reactive reagents, such as hexamethylphosphorous triamide or organolithiums.The photoreaction of 15c did not give the corresponding styrene, but afforded several products containing 2,4,6-tri-t-butylbenzothiophene and Dewar benzenes,2,2-di-t-butyl-3-(3,4,6-tri-t-butylbicyclohexa-2,5-dien-2-yl)thiirane and 2-t-butyl-3,3-dimethyl-1-(1,3,5-tri-t-butylbicyclohexa-2,5-diene-2-yl)-1-butene (24), the latter of which is the first example for a vinyl-substituted Dewar benzene.Compound 24 has a unique reactivity, giving a rearrangement product, 2-t-butyl-3,3-dimethyl-1-(1,3,5-tri-t-butylbicyclohexa-2,5-diene-2-yl)-1-butene on thermolysis.
