Azacalix[4]arene tetramethyl ether with inherent chirality generated by substitution on the nitrogen bridges

Ishibashi, Koichi; Tsue, Hirohito; Takahashi, Hiroki; Tamura, Rui

doi:10.1016/j.tetasy.2009.01.017

Cited by 44 publications

(34 citation statements)

References 35 publications

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“…The first inherently chiral nitrogen-bridged azacalix [4]arene was prepared in an intramolecular cyclization via Buchwald-Hartwig amination by Ishibashi and co-workers in 2009, as shown in Scheme 34. 75 Several chiral phosphane ligands were screened towards the cyclization…”

Section: Formation Inherently Chiral Calixarenesmentioning

confidence: 99%

Synthesis and Application of Chiral Palladium-Phosphane Precatalyst in Enantioselective C-N Cross-Coupling

Wright¹

2021

Preprint

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The various strategies and reaction conditions towards the synthesis of benzene-, naphthalene-, and phenanthrene-based dicyclohexylbiaryl phosphanes are presented. A chiral third generation Buchwald-type precatalyst has been synthesized, employing the non-commercially available ligand, (R)-dicyclohexyl(2'-methoxy-[1,1'-binaphth-2-yl])phosphane, (R)-Cy2MOP, and a dimeric methanesulfonate-bridged palladacycle based on a 2-aminobiphenyl scaffold. Application of the palladacyclic precatalyst in an enantioselective variant of the BuchwaldHartwig reaction is demonstrated in the desymmetrization of prochiral α-(2-bromobenzyl)malonamides via intramolecular N-arylation. The scope of the catalysis in the presence of the precatalyst has been investigated with efforts towards optimizing yields, catalyst loading, and enantioselectivities. Attempts towards the isolation of a potential reaction intermediate in the form of a stable amido-bound palladium complex are discussed. Finally, strategies towards gaining mechanistic insight on the origin of the enantiomeric excess are discussed.

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Section: Formation Inherently Chiral Calixarenesmentioning

confidence: 99%

Synthesis and Application of Chiral Palladium-Phosphane Precatalyst in Enantioselective C-N Cross-Coupling

Wright¹

2021

Preprint

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“…232-234 8C; 1 HNMR (250 MHz,[D 6 0, 129.0, 128.5, 128.1 (d, 4 J(C,F) = 0.9 Hz), 126.8, 126.2 (d, 2 J(C,F) = 10.0 Hz), 104.2 ppm (d, 2 J(C,F) = 26.9 Hz);C 18 H 14 4,6,17,8,15,arene (4 a):Asolution of 3a (1.06 g, 2.26 mmol, 1.05 equiv) and 2b (650 mg, 2.12 mmol, 1equiv) in acetonitrile (30 mL) was stirred before N-ethyldiisopropylamine (1.2 mL, 6.93 mmol, 3.3 equiv) was added dropwise. The mixture was heated to reflux for 22 h, then stirred at 0 8Cf or 1h.T he resulting precipitated solid was filtered, washed successively with acetonitrile (40 mL), hot water (40 mL 176.7, 147.3, 147.2, 136.1, 132.5, 131.1, 130.9, 129.0, 127.4, 126.7, 124.1, 124.1, 98.8, 39.0, 27.1 ppm;C 34 H 34 4,6,16,12,22,8,14,20tetraazacalix[4]arene (7):Asolution of azacalixarene 6 (100 mg, 0.16 mmol, 1equiv) and propionyl chloride (0.12 mL, 1.3 mmol, 8equiv) in acetonitrile (200 mL) was stirred under argon for 1h at RT before N-ethyldiisopropylamine (0.23 mL, 1.3 mmol, 8equiv) was added dropwise. The mixture was heated to reflux overnight.…”

Section: Generalr Emarksmentioning

confidence: 99%

“…The solvent was evaporated to dryness and the residue was triturated in water and filtered. Ar 32, 133.97, 127.92, 127.56, 126.97, 124.78, 119.56, 94.77, 28.68, 9.36 4,6,16,12,22,8,14,arene (8):Asolution of azacalixarene 6 (150 mg, 0.25 mmol, 1equiv) and butyryl chloride (0.10 mL, 1.0 mmol, 4equiv) in acetonitrile (50 mL) was stirred under argon for 1h at RT before N-ethyldiisopropylamine (0.17 mL, 1.0 mmol, 4equiv) was added dropwise. The mixture was heated to reflux overnight.…”

Section: Generalr Emarksmentioning

confidence: 99%

“…Severals upramolecular assemblies of azacalixarenes were shownt ob eb uilt on interactions involving the bridging nitrogen atoms, such as hydrogenb onds [9] or Se···N noncovalent interactions. [10] N-Alkylation is ap owerful tool to build more sophisticated receptors, [11] and this approachc an also be used to inducea ni nherent chirality [12] or to improve the macrocycle solubility. [13] Oxidationo fa zacalixarene derivatives can produce stabler adical cations,h igh-spin diradicals, or polycationic species because the N-atom can act as as pin-bearing site and the nitrogenl one pair of each bridging atom is effectively conjugated with one or multiple neighboring aryl units.…”

Section: Introductionmentioning

confidence: 99%

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1,3‐Alternate Tetraamido‐Azacalix[4]arenes as Selective Anion Receptors

Canard

Edzang

Chen

et al. 2016

Chemistry A European J

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Six tetraaza[1.1.1.1]cyclophane derivatives bearing peripheral amide groups were prepared according to two distinct synthetic strategies that depend on the connection pattern between the aryl units. NMR experiments combined with the X-ray structures of two tetraamide derivatives 4 b and 10 show that these cavitands adopt a 1,3-alternate conformation both in solution and in the solid state. Consequently, the four amide groups of the aza[1.1.1.1]-m,m,m,m-cyclophane isomer 10 can contribute to the same recognition process towards neutral water molecules or anion guests. NMR experiments, mass spectrometry analyses and single-crystal X-ray structures confirm the anion-binding ability of this receptor. Absorption spectrophotometric titrations in nonpolar solvents provided evidence for the selectivity of 10 to chloride anions in the halide series, with a corresponding association constant Ka reaching 2.5 × 10(6) m(-1).

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“…Pillarenes, [62][63][64] in which benzene rings are linked by para, and not by meta positions as in calixarenes should also be included. A special group are the thia, oxa and azacalixarenes, in which the linking methylene groups of calixarenes are formally replaced by sulfur, [65][66][67] oxygen, [68][69][70] or nitrogen, [71][72][73] atoms, respectively.…”

Section: Introductionmentioning

confidence: 99%