A Stable Neutral Silaaromatic Compound, 2-{2,4,6-Tris[bis(trimethylsilyl)methyl]phenyl}- 2-silanaphthalene

Synthesis and Properties of an Overcrowded Silabenzene Stable at Ambient Temperature

“…Direct coupling of ethylene with the proper acetylenes under Pauson ± Khand conditions provides an efficient and economical method for preparing synthetically useful cyclopentenones. [5] Pauson ± Khand reactions of ethylene with stoichiometric amounts of hexacarbonyldicobalt ± alkyne complexes have been reported. [6,7] Rautenstrauch et al described the first catalytic Pauson ± Khand reaction between heptyne and ethylene in toluene in 1990.…”

“…The SiÀC2 bond length in 2 is 1.777 , which is a middle value between Si À C single and double bonds, and is similar to the average value of two SiÀC bond lengths of 2-silanaphthalene (calculated to be 1.750 and 1.791 ). [5] Other CÀC bond lengths in 2 (C2ÀC3 1.401 ; C3ÀC4 1.402 ) are found to be almost the same as those of benzene (1.39 ± 1.40 ). [1] No change was observed in its NMR spectrum even after the [D 12 ]cyclohexane solution of 1 was stored for many weeks at room temperature under an inert atmosphere.…”

“…Märkl et al [4] previously reported the synthesis of 2,6-bis(trimethylsilyl)-1,4-di-tert-butylsilabenzene, but it was reported as stable only below À 100 8C in solution (THF/Et 2 O/petroleum ether, 4/1/1) and, judging from its relatively high field 29 Si NMR chemical shift (d 26.8), stabilized by the coordination of a Lewis-base solvent (see below). In contrast, we have recently succeeded in the synthesis of the first stable silabenzenoid compound, 2-silanaphthalene, [5] by protecting its reactive silicon center with an extremely bulky substituent group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (ªTbtº). We report here the synthesis and characterization of the stable silabenzene bearing the Tbt group 1.…”

“…These reactions of 1 as a 1,3-diene are clearly different from those of 2(Tbt)-2-silanaphthalene, which reacted only as unconjugated SiÀC double bond with several reagents. [5] The NMR signals due to the silabenzene ring of 1 were assigned by 2D NMR techniques and the results are shown in Table 1 [12] and lies between the two 1 J SiÀC values obtained for 2(Tbt)-silanaphthalene (92 and 76 Hz).…”

Photochemical reaction of silyl‐substituted 1,4‐disila(dewar‐benzene) with isocyanide and phenylacetylene

“…Several silaaromatic compounds have recently been synthesized, and their unique structures, reactivity, and aromaticity have been extensively studied [1][2][3]. Very recently, we have succeeded in isolating a stable 1,2-disilabenzene derivative for the Correspondence to: Akira Sekiguchi; e-mail: sekiguch@chem.…”