Binaphthyl Rings Research Articles

Design of Binaphthyl‐Modified Symmetrical Chiral Phase‐Transfer Catalysts: Substituent Effect of 4,4′,6,6′‐Positions of Binaphthyl Rings in the Asymmetric Alkylation of a Glycine Derivative

A series of symmetrical chiral phase-transfer catalysts with 4,4',6,6'-tetrasubstituted binaphthyl units have been designed, and these aryl- and trialkylsilyl-substituted phase-transfer catalysts, which included a highly fluorinated catalyst, were prepared. The chiral efficiency of these chiral phase-transfer catalysts was investigated in the asymmetric alkylation of tert-butylglycinate-benzophenone Schiff base under mild phase-transfer conditions, and the eminent substituent effect of the 4,4',6,6'-positions of the binaphthyl units on enantioselection was observed. In particular, the OctMe2Si-substituted catalyst was found to be highly efficient for the phase-transfer alkylation of tert-butylglycinate-benzophenone Schiff base with various alkyl halides, including sec-alkyl halides. The highly fluorinated catalyst was also utilized as a recyclable chiral phase-transfer catalyst by simple extraction with fluorous solvents.

Highly Twisted Helical Polyacetylene with Morphology Free From the Bundle of Fibrils Synthesized in Chiral Nematic Liquid Crystal Reaction Field

We synthesized novel axially chiral binaphthyl derivatives with highly twisting powers by substituting phenylcyclohexyl (PCH) mesogenic moieties into 2,2' positions or 2,2',6,6' positions of binaphthyl rings. The di- and tetrasubstituted binaphthyl derivatives, abbreviated as D-1 and D-2, respectively, were adopted as chiral dopants to induce chiral nematic liquid crystals (N*-LCs) available for synthesis of helical polyacetylene. The helical twisting power (betaM) of D-2 was 449 microm(-1), which was ca. 2.6 times larger than that of D-1 (171 microm(-1)). We prepared two kinds of induced N*-LCs with 5 microm and 270 nm in helical pitch by adding the chiral dopants D-1 and D-2 into the host N-LCs, respectively. The helical polyacetylene synthesized in the N*-LC containing D-2 exhibited highly screwed fibrils, but not a bundle of fibrils. This result is in quite contrast to the usual fibril morphology, where the screwed fibrils are gathered to form the bundle of fibrils, as observed in the helical polyacetylene synthesized in the N*-LC containing a chiral dopant with moderate helical twisting power, such as D-1. It is of keen interest that the helical pitch (270 nm) of the N*-LC including D-2 is much smaller than the diameter (ca. 1 microm) of the bundle of fibrils, which should depress the formation of the bundle of fibrils. The morphology free from the bundle of fibrils might enable us to evaluate more precisely intrinsic electromagnetic properties of a single screwed fibril of helical polyacetylene.

Syntheses of highly twisted helical polyacetylene under nano-order chiral nematic liquid crystal reaction field

Abstract We synthesized novel mesogenic axially chiral binaphthyl derivative by substituting phenyl-cyclohexyl (PCH) moieties into 2, 2′, 6 and 6′ positions of binaphthyl rings. The binaphthyl derivative showed the highest twisting power of β M = 381.87 μm −1 , when 0.05 mol% of the chiral dopant was added into a mixture of PCH302 and PCH304. The helical pitches of N ∗ -LC varied from 270 to 350 nm with changes of the concentration of the chiral dopant from 1.5 to 1.0 mol%. These helical pitches are smaller one-tenth than those (2–5 μm) observed in the N ∗ -LC containing di-substituted binaphthyl derivatives. This indicates that the present N ∗ -LC including tetra-substituted binaphthyl derivatives is feasible for much higher twisted asymmetric reaction field. It is of interest that the polyacetylene film synthesized in the N ∗ -LC with helical pitch of 270 nm showed highly screwed fibrils, but not the bundle of fibril. This is due to the fact that the helical pitch of 270 nm is smaller than the diameter of the bundle of fibril. This situation might depress the formation of the bundle of fibril. The fibrillar morphology without the bundle of fibrils should make it much easier to evaluate electromagnetic properties of the screwed fibril.

A parallel colorimetric method for the rapid discovery and optimization of heterogeneous hydrodesulfurization catalysts.

A spectrophotometric based, parallel approach to screen heterogeneous catalysts for hydrodesulfurization has been developed. The method utilizes optical changes resulting from the hydrodesulfurization of 1,1'-binaphthothiophene to 1,1'-binaphthyl to determine catalyst activity. Hydrodesulfurization of 1,1'-binaphthothiophene to 1,1'-binaphthyl results in a loss of conjugation in the binaphthyl ring system. This results in a blue shift of more than 60 nm in the UV-vis spectrum. Since only small amounts of the HDS catalyst and 1,1'-binaphthothiophene are required, a large number of catalysts may be screened simultaneously. The synthesis of the 1,1'-binaphthothiophene and conditions for HDS catalyst screening are described.

Effect of the alkyl chain length of 1,1′-binaphthyl esters in lipase-catalyzed amidation

Lipase-catalyzed amidation of 2-[2-(ethoxycarbonyl)ethyl]-1,1′-binaphthyl [ (±)- 3 ] yielded optically active ( S)- 3 and 2-[2-(2-cyanoethylaminocarbonyl)ethyl]-1,1′-binaphthyl [ ( R)- 6a ] with high enantiomeric excess. For these lipase-catalyzed amidations, the optimal alkyl chain length between the binaphthyl ring and the ester group was determined to be an ethylene spacer.

Synthesis of Liquid Crystalline Binaphthyl Derivatives

We present the first liquid crystalline (LC) binaphthyl derivatives, in which the rigid rod-like substituents containing phenylcyclohexyl mesogenic cores are introduced into the 2, 2′, 6, and 6′ positions of the chiral binaphthyl rings. The binaphthyl derivatives show enantiotropic smectic A phase, but neither chiral nematic nor chiral smectic phase. The present quadri-substituted binaphthyl derivatives gave larger values in twisting power (βM), compared with the non-substituted and di-substituted binaphthyl derivatives.

Methyl 3',6'-Bis(chloromethyl)-2,2'-dimethoxy-1,1'-binaphthalene-3-carboxylate

The dihedral angle between the naphthalene ring systems in the title compound, C26H22Cl2O4, is 97.0 (1)°. The methoxycarbonyl group is disordered over two positions and is twisted out of the plane of the attached binaphthyl ring system in both cases. The molecules are joined together through weak C4′—H4′⋯O2 and C4′—H4′⋯O2A(−x + {1\over 2},y + 1/2,-z + {1\over 2}) hydrogen bonds, and by stacking interactions between the methoxycarbonyl groups along the a direction.

Synthesis of gossypol and gossypol derivatives

AbstractThe synthesis of gossypol and certain major degradation products possessing the binaphthyl ring carbon skeleton is discussed.