Planar Chiral Triazole‐Based Phosphanes Derived from [2.2]Paracyclophane and Their Activity in Suzuki Coupling Reactions

Abstract

In this communication we report the short synthesis of a variety of planar chiral triazole‐based phosphanes. These molecules have been readily prepared from 4‐azido[2.2]paracyclophane in two steps. It was observed that the stability of the resulting phosphanes was dependent on the C‐4 substituent. The efficacy of the new phosphanes in the palladium‐mediated Suzuki–Miyaura coupling reaction was evaluated. The phosphanes proved to be more effective than previously prepared planar chiral [2.2]paracyclophane‐based phosphanes.

[2.2]Paracyclophane‐Bis(triazole) Systems: Synthesis and Photochemical Behavior

“…The solvent was removed in vacuo and the resulting residue was separated by flash chromatography on silica gel, yielding triazole 11 (Scheme ). By replacing acetylene 1 by phenylacetylene, or azide 8 by phenylazide, and lowering the reaction temperature to 60 °C, previously described derivative 12 and triazole 13 were synthesized (Scheme ). The most prominent signal in the 1 H NMR spectra of compounds 11 – 13 belongs to the triazole proton, which appears as a sharp singlet, around δ =8.00 ppm.…”

An Asymmetric Variant of the Bischler–Möhlau Indole Synthesis

“…[18] Unusually, the diphenylphosphane derivative 9a is more effective than the bulky, electron rich dicyclohexylphosphane 9b in most of the limited examples assayed; this mirrors the results of Kwong. [25] It is promising that both couple the more challenging aryl halides such as the sterically demanding 2-bromo-1,3dimethylbenzene (Table 3, Entry 3) and the electron rich 2-bromoanisole (Table 3, Entry 4) even though the coupling conditions have not been optimised.…”

“…[2,[9][10][11][12] Many racemic heterocyclic [2.2] paracyclophane derivatives have been reported but few have been resolved and as a result their full potential has not been realised. [13] We have a long standing interest in the preparation of planar chiral heterocycles having synthesised [2.2]paracyclophane-derived benzimidazoles, [14] imidazoles, [15] pyridines, [16,17] triazoles, [18] and a benzothiazole. [19] All, with the exception of the benzimidazoles, have been prepared in enantiomerically enriched form.…”

The synthesis of substituted amino[2.2]paracyclophanes

“…Rf (4/1 Hex/EtOAc) 0.70 1 H NMR (500 MHz, CDCl3 J = 7.9, 1.9 Hz), 6.67 (1H, d, J = 7.9 Hz), 6.58 (1H, dd, J = 7.9, 1.8 Hz), 6.43 (1H, dd, J = 7.9, 1.9 Hz), 6.42 (1H, d, J = 7.6 Hz), 6.37 (1H, dd, J = 7.9, 1.9 Hz), 4.06 (1H, ddd, J = 12.2, 10.1, 1.4 Hz), 3.33 (1H, ddd, J = 13.6, 10.1, 3. (24). A mixture of hydroxyl amine hydrochloride (0.21 g, 3.0 mmol, 3.0 eq.)…”

“…Bolm indicated that the copper-mediated coupling of 4-bromo [2.2]paracyclophane and pyrazole failed 31 although Paradies 12 showed that analogous conditions could give the pseudo-gem amino pyrazole but not the imidazole. We have briefly reported the copper-mediated amination of 4-bromo [2.2]paracyclophane 24 and present a more detailed study below. Ortner has reported an interesting but low yielding transition metal-free amination.…”