Potential 1,1′-binaphthyl NLO-phores with extended conjugation between positions 2 and 6, and 2′ and 6′

A synthetic approach is reported which allows independent introduction of alkynyl groups to positions 2,2′ and then to 6,6′ of binaphthyls. The approach is based on the high selectivity of the Stephens-Castro alkynylation of 6,6′-dibromo-2,2′-diiodo-1,1′-binaphthyl. The tetraalkynylated derivatives exhibit extended conjugation between groups at positions 2 and 6, and 2′ and 6′, achieved by overcoming steric hindrance at positions 2 and 2′ by using alkynyl spacers.     

A new route to 2,2′,3,3′-tetrasubstituted binaphthyls

Based on an ortho-lithiation protocol of 2,2′-dibromo-1,1′-binaphthyl four tetrasubstituted binaphthyls, 2,2′-dibromo-3,3′-diiodo-, 3,3′-dibromo-2,2′-diiodo-, 2,2′,3,3′-tetrabromo-, and 2,2′,3,3′-tetraiodo-1,1′-binaphthyls have been prepared in excellent yield which in turn proved to be versatile key intermediates in the synthesis of various 2,2′,3,3′-tetrasubstituted 1,1′-binaphthyl derivatives.     

Intramolecular [3+2] cycloaddition reaction of α,β-enoate derivatives having allylsilane parts: 1,1′-biphenyl-2,2′-di(triflyl)amide (BIPAM)+2Me2AlCl as a novel Lewis acid

The bidentate Lewis acid generated by mixing 1,1′-biphenyl-2,2′-di(triflyl)amide (BIPAM) and 2 M equiv of Me₂AlCl can efficiently promote the intramolecular [3+2] cycloaddition reaction of α,β-enoate derivatives having ester tether linking α,β-unsaturated ester and allylsilane parts.     

Preparation of a series of novel fluorophores, N-substituted 6-amino and 6,6″-diamino-2,2′:6′,2″-terpyridine by palladium-catalyzed amination

A new series of N-substituted 6-amino- and 6,6″-diamino-2,2′:6′,2″-terpyridine (6-amino- and 6,6″-diamino-tpy) was conveniently synthesized in one-step by Pd-catalyzed amination of bromo-substituted tpys with various amines. For highly coordinating tpy substrates, use of appropriate chelating phosphine ligand was critical to achieve moderate to satisfactory yield. The prepared N-substituted 6-amino- and 6,6″-diamino-tpys exhibited moderate to intense fluorescence in dichloromethane with fine-tuned fluorescence maxima ranging from 385 to 455 nm.     

Improved synthesis of 2,2′-dimethoxy-1,1′-binaphthyl-3,3′-diacetic acid derivatives

During the past decade, the chemistry of BINAP, BINAM, and BINOL derivatives experienced an important development due to multiple applications in catalysis, metallo-supramolecular chemistry and material science. Consequently, the need to develop functionalized binaphthyl derivatives became crucial. In this context, we were interested in preparing 2,2′-dimethoxy-1,1′-binaphthyl-3,3′-diacetic acid species. The latter were efficiently prepared using a modified Arndt-Eistert reaction that afforded the expected chiral diacid in good yield. Compared to the method we described earlier, this new strategy allows the preparation of the target homologated diacid chloride in a very efficient manner, limiting wastes and tedious column chromatographies.     

New N-acyl, N-alkyl, and N-bridged derivatives of rac-6,6′,7,7′-tetramethoxy-1,1′,2,2′,3,3′,4,4′-octahydro-1,1′-bisisoquinoline

The preparation of potential new ligand systems based on the rac-1,1′,2,2′,3,3′,4,4′-octahydro-6,6′,7,7′-tetramethoxy-1,1′-bisisoquinoline skeleton has been investigated. Syntheses of N-(2-bromobenzyl), N-(3-acetoxybenzyl), N-acetyl, N-chloroacetyl, N-chlorocarbonyl, N-ethoxycarbonyl and N-tert-butyloxycarbonyl derivatives and five macrocyclic, polyether containing derivatives are described.     

Synthesis of spirobiindanes via bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids

Bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids (HPAs) was examined for the first time, and a series of spirobiindanes were synthesized. 1,5-Diaryl-3-pentanones were refluxed and dehydrated in toluene in the presence of 0.15 equiv of a heteropoly acid to furnish spirobiindanes in moderate to high yield. For the known 4,4′-dibromo-7,7′-dimethoxy-1,1′-spirobiindane, the yield was upgraded from 66% to 80%.     

(R)-6,6′-Bis(trifluoromethanesulfonyl)-2,2′-dihydroxy-1,1′-binaphthyl: a new ligand for asymmetric synthesis

The new (R)-6,6′-bis(trifluoromethanesulfonyl)-2,2′-dihydroxy-1,1′-binaphthyl (1) has been synthesized and proved to generate highly active zirconium-based catalysts for asymmetric Mannich-type reactions.     

5,5′-二甲基-2,2′-二茚满-1,1′,3,3′-四酮的合成及结构表征

本文以4-甲基邻苯二甲酸酐为原料, 成功地合成了5,5′-二甲基-2,2′-二茚满-1,1′,3,3′-四酮(2). 通过元素分析、核磁共振、红外光谱及质谱等测试手段, 确定了化合物2的结构与存在形式, 通过ESR测试发现化合物2具有顺磁性.     

Synthesis and characterizations of 3,3′-bis(diphenylphosphinoamine)-2,2′-bipyridine and 3,3′-bis(diphenylphosphinite)-2,2′-bipyridine and their chalcogenides

New bis(phosphinoamine) and bis(phosphinite) derivatives of 2,2′-bipyridine were prepared through a single step reaction of 3,3′-diamino-2,2′-bipyridine or 3,3′-dihydroxy-2,2′-bipyridine with diphenylchlorophosphine, respectively. Their P = E chalcogenides (E = O, S, Se) were also prepared. All the new compounds were characterized by elemental analysis, IR and NMR spectroscopies. The molecular structure of 3,3′-bis(diphenylthiophosphinite)-2,2′-bipyridine was elucidated by single-crystal X-ray crystallography.     

One-pot synthesis of 5,5′-dibromo-2,2′-dipyridylacetylene and its boronic acid derivative

5,5′-Dibromo-2,2′-dipyridylacetylene was prepared from 2,5-dibromopyridine and (trimethylsilyl)acetylene via the new one-pot synthesis approach using a regioselective palladium-catalyzed coupling reaction with a 60% yield. Several protocols of lithium-halogen exchange were then attempted to synthesize 6,6′-(1,2-ethynediyl)bis[3-pyridylboronic acid] from 5,5′-dibromo-2,2′-dipyridylacetylene. The former was successfully obtained with a 54% yield by a reverse addition method using toluene and THF and it showed potential as a useful building block for cross-coupling reactions in the formation of carbon-carbon bonds.     

Facile synthesis of 6-iodo-2,2′-dipivaloyloxy-1,1′-binaphthyl, a key intermediate of high reactivity for selective palladium-catalyzed monofunctionalization of the 1,1′-binaphthalene core

A high-yielding procedure for selective monoiodination of 2,2′-dihydroxy-1,1′-binaphthyl (BINOL) is reported. 6-Iodo-2,2′-dipivaloyloxy-1,1′-binaphthyl, obtained in three steps starting from BINOL in 88% overall yield, proved to be a highly efficient substrate in various palladium-catalyzed coupling (Stille, Heck, Sonogashira, and Suzuki coupling) and carbonylation reactions compared to the analogous 6-bromo derivative.     

2,2′-Bipyridine-6,6′-diyl bisnitroxide as a paramagnetic host: Encapsulation of a zinc(II) ion

A chelate complex of zinc(II) and 2,2′-bipyridine-6,6′-diyl bis(tert-butyl nitroxide) (bpybNO) with a metal/ligand ratio of 1/2 was structurally characterized to be [Zn(bpybNO)₂][Zn(hfac)₃]₂, where Hhfac stands for 1,1,1,5,5,5-hexafluoropentane-2,4-dione. The magnetic susceptibility measurement indicates the presence of considerable antiferromagnetic interaction among the four S = 1/2 spins. The exchange parameter J was estimated as 2J/k_B = −103(1) K, on the basis of a tetrahedral coupling model. The antiferromagnetic coupling is stronger after complexation than before. The density-functional theory calculation on related model compounds supports the present analysis and clarified the role of the zinc ion as a superexchange coupler.     

Highly efficient synthesis of 2′,3′-didehydro-2′,3′-dideoxy-β-nucleosides through a sulfur-mediated reductive 2′,3′-trans-elimination. From iodomethylcyclopropanes to thiirane analogs

Taking into account the thiophilic properties of iodine, a very simple methodology to achieve 2′,3′-didehydro-2′,3′-dideoxy-β-nucleosides in high yield was performed, using mild, and inexpensive conditions, by means of the treatment of 2′-deoxy-3′,5′-dibenzoyl-2′-iodo-β-nucleoside derivatives with NaHS. The process has shown to be highly dependent of the relative geometry between the iodine atom and the adjacent leaving group. In this way, different essays carried out with pyranose derivatives have concluded in no reaction when the vicinal groups to eliminate do not adopt a trans-diaxial disposition. In addition, the treatment of 2-iodomethyl-cyclopropane-1,1-dicarboxylic acid diethyl ester under the same conditions softly and readily leads to the obtention of a mixture of the expected 2-allyl-malonic acid diethyl ester (as the minor product) and the thiirane derivative 2-thiiranylmethyl-malonic acid diethyl ester (as the major product). In this case, the responsible of the reaction progress are the nucleophilic properties of the sulfur atom rather than the thiophilic character of the iodine atom.     

Copper(I) halide complexes with 2,2′-bis(diphenylphosphano)-1,1′-binaphthyl (rac-binap) and heterocyclic thiones. Racemic compounds in chiral and achiral crystal space groups

Reactions of copper(I) halides with racemic 2,2′-bis(diphenylphosphano)-1,1′-binaphthyl (rac-binap) in 1:1 molar ratio afforded mononuclear complexes of the type [CuX(rac-binap)] (X = Cl, Br, I) which, on further treatment with 1 equiv. of pyridine-2-thione (py2SH), pyrimidine-2-thione (pymtH) or 4,6-dimethyl-pyrimidine-2-thione (dmpymtH) gave rise to the formation of mixed-ligand complexes of the formula [CuX(rac-binap)(thione)]. The molecular structures of [CuBr(rac-binap)(py2SH)] · 2CH₂Cl₂, [CuBr(rac-binap)(py2SH)] · CH₂Cl₂ and [CuBr(rac-binap)(dmpymtH)] · CH₂Cl₂ have been established by single-crystal X-ray diffraction. Each of the complexes features a distorted tetrahedral copper(I) center with the phosphane acting in a chelating fashion. The complexes are strongly luminescent in the solid state at ambient temperature. Unusually, the [CuBr(rac-binap)(py2SH)] · 2CH₂Cl₂ molecules crystallise in a chiral space group with independent S- and R-enantiomers in the asymmetric unit.     

An effective method for the preparation of mono N-alkyl derivatives of 1,1′-bis(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline)

The condensation of 1,1′-bis(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline) with alkyl, aralkyl and aryl aldehydes, but not ketones, in ethanol or chloroform provides useful cyclic aminal [8-substituted 5,6,10,11,15b,15c-hexahydro-2,3,13,14-tetramethoxy-8H-imidazo[5,1-a:4,3-a′]diisoquinoline] intermediates that when subsequently treated with sodium cyanoborohydride in ethanol, followed by the addition of 2 M hydrochloric acid, gave monosubstituted N-alkyl 1,1′-bis(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline) derivatives in very high yields. The rates of the initial condensation with four different aldehydes were measured, and the entire sequence was successfully applied in one example to a ‘one-pot’ process; this signals a versatile route to differentially N-substituted 1,1′-bis(1,2,3,4-tetrahydroisoquinoline) derivatives.     

Synthesis and X-ray structures of new chiral Ag(I) complexes with biaryl-based N4-donor ligands

Condensation of (R)-2,2′-diamino-1,1′-binaphthyl or (R)-6,6′-dimethylbiphenyl-2,2′-diamine with 2 equiv of 2-pyridine carboxaldehyde in toluene in the presence of molecular sieves at 70 °C gives (R)-N,N′-bis(pyridin-2-ylmethylene)-1,1′-binaphthyl-2,2′-diimine (1), and (R)-N,N′-bis(pyridin-2-ylmethylene)-6,6′-dimethylbiphenyl-2,2′-diimine (3), respectively, in good yields. Reduction of 1 with an excess of NaBH₄ in a solvent mixture of MeOH and toluene (1:1) at 50 °C gives (R)-N,N′-bis(pyridin-2-ylmethyl)-1,1′-binaphthyl-2,2′-diamine (2) in 95% yield. Rigidity plays an important role in the formation of helicate silver(I) complexes. Treatment of 1, or 3 with 1 equiv of AgNO₃ in mixed solvents of MeOH and CH₂Cl₂ (1:4) gives the chiral, dinuclear double helicate Ag(I) complexes [Ag₂(1)₂][NO₃]₂ (4) and [Ag₂(3)₂][NO₃]₂ · 2H₂O (6), respectively, in good yields. While under the similar reaction conditions, reaction of 2 with 1 equiv of AgNO₃ affords the chiral, mononuclear single helicate Ag(I) complex [Ag(2)][NO₃] (5) in 90% yield. [Ag₂(1)₂][NO₃]₂ (4) can further react with excess AgNO₃ to give [Ag₂(1)₂]₃[NO₃]₂[Ag(CH₃OH)(NO₃)₃]₂ · 2CH₃OH (7) in 75% yield. All compounds have been fully characterized by various spectroscopic techniques and elemental analyses. Compounds 1 and 5-7 have been further subjected to single-crystal X-ray diffraction analyses.     

Intramolecular diamination and alkoxyamination of alkenes with N-sulfonyl ureas employing N-iodosuccinimide

Reaction of N-δ-alkenyl-N′-sulfonyl urea 1 with N-iodosuccinimde (NIS; 2 equiv) and a catalytic amount of AgOTf (20 mol %) at room temperature led to intramolecular alkoxyamination to form bicyclic isourea 2a in 95% isolated yield. In comparison, reaction of 1 with NIS and sodium bicarbonate (1 equiv) at room temperature led to isolation of bicyclic imidazolidin-2-one 2b in 91% yield. These NIS-mediated alkoxyamination and diamination protocols were effective for a range of N-δ-alkenyl-N′-sulfonyl ureas to form the corresponding heterobicyclic compounds in good yield with high chemoselectivity and good to excellent diastereoselectivity.     

A convenient synthesis of 6,6′-dimethyl-2,2′-bipyridine-4-ester and its application to the preparation of bifunctional lanthanide chelators

We describe a convenient scalable synthesis of 4-carbomethoxy-6,6′-dimethyl-2,2′-bipyridine based on the application of modified Negishi cross-coupling conditions. The use of this building block in the preparation of a number of dissymmetrically 6,6′-trisubstituted-2,2′-bipyridines and of bifunctional lanthanide chelators is also reported.     

Rapid atropisomerization of 1,1′:5′,1″-ternaphthalene-2,2′,6′,2″-tetrol (TERNOL) and its inhibition by tethering at positions 7 and 7″

Atropisomerization of 1,1′:5′,1″-ternaphthalene-2,2′,6′,2″-tetrol (TERNOL) is very fast under basic conditions. The stereochemical instability is attributed to the nature of oxide anion of the central 2,6-naphthodiol moiety. Ring-closing metathesis of 7,7″-diallyloxy TERNOL results in intramolecular tethering in a high yield, which intrinsically inhibits the rapid isomerization. Bidentate sites in the tethered TERNOL are proved to have enough structural flexibility as an axial chiral ligand.