Sodium tert-butoxide mediates the coupling of aryl halides with benzene derivatives without the aid of transition metal catalysts but with a catalytic 1,10-phenanthroline derivative.
The transition-metal-catalyzed cross-coupling of aryl halides (ArÀX) with aryl metal reagents is one of the most reliable and widely applicable methods for biaryl synthesis. The catalytic cycle involves a two-electron reduction of ArÀX upon its oxidative addition to a low-valent transition metal.[1] Such a reduction is crucial for the employment of Ar À X as an electrophile in substitution reactions because Ar À X cannot undergo S N 1 or S N 2 reactions. A single-electron reduction also is effective for the activation of ArÀX, which is converted into [ArÀX] C À then into ArC with elimination of X À . [2,3] ). [5,6] Herein, we report the coupling of aryl halides with aryl Grignard reagents that does not require the aid of transition metals and goes through an S RN 1 mechanism. [7, 8] The reaction of phenylmagnesium bromide (1 a; 2 equiv) with 2-iodonaphthalene (2 m; 1 equiv) in THF at 60 8C for 24 h, after quenching with D 2 O, gave 2-deuterionaphthalene (23 %, > 95 % deuteration) and iodobenzene (16 %) in addition to a small amount (2 %) of 2-phenylnaphthalene (3 am), with 29 % conversion of 2 m (Table 1, entry 1). This result shows that I/Mg exchange giving 2-naphthylmagnesium bromide and iodobenzene predominates, but the crosscoupling also takes place. The selectivity for the crosscoupling over the I/Mg exchange was drastically improved by changing the reaction solvent from THF to toluene, although a higher temperature (110 8C) was required (Table 1, entries 2 and 3). The Grignard reagent 1 a was prepared in THF and most of the solvent was removed in vacuo, and then it was used for the reaction with 2 m in toluene at 110 8C for 24 h to give 3 am in 93 % yield.
The magnetization reversal process of an ordered Co nanorod array is shown using the images obtained from successive in-field magnetic force microscope (MFM) measurements. The magnetization reversal model is discussed according to local and whole magnetization reversal properties measured by the polar magneto-optical Kerr effect (PMOKE) and an alternating gradient magnetometer (AGM), respectively. Additionally, the dipolar field was probed using in-field MFM measurements. By removing the effect of the dipolar field, an intrinsic switching field distribution (SFD) is shown in a map with a hexagonal array. A detailed study of the dipolar field in ordered nanorod arrays with various diameters and pitches was carried out by numerical calculations.
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