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.     

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.     

Scandium triflate-catalyzed 6,6′-diiodination of 2,2′-dimethoxy-1,1′-binaphthyl with 1,3-diiodo-5,5-dimethylhydantoin

Scandium triflate-catalyzed iodination of 2,2′-dimethoxy-1,1′-binaphthyl with 2 equiv of 1,3-diiodo-5,5-dimethylhydantoin (DIH) proceeded to give 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl in 98% yield and subsequent deprotection of methyl groups provided 6,6′-diiodo-1,1′-binaphthol, which is a useful ligand or reagent for many enantioselective transformations. Use of 2 equiv of NIS in place of DIH in the presence of scandium triflate, however, did not successfully yield 6,6′-diiodo-2,2′-dimethoxy-1,1′-binaphtyl, indicating that one of two types of iodine atoms in DIH is more reactive toward the iodination than iodine in NIS.     

Synthesis of 5,5′-diarylated 2,2′-bithiophenes via palladium-catalyzed arylation reactions

2,2′-Bithiophene and 3,3′-dicyano-2,2′-bithiophenes are diarylated directly with aryl bromides at the 5- and 5′-positions accompanied by C-H bond cleavage in the presence of Pd(OAc)₂ and a bulky phosphine ligand using Cs₂CO₃ as base. In the reaction using (2,2′-bithiophen-5-yl)diphenylmethanol as the substrate, monoarylation at the 5-position via C-C bond cleavage occurs selectively to give 5-aryl-2,2′-bithiophenes and the subsequent arylation with a different aryl bromide affords the corresponding unsymmetrically 5,5′-diarylated products.     

The highly regiospecific synthesis and crystal structure determination of 1,1′-2,5′ substituted ring-locked ferrocenes

1,1′-Ferrocene biscarboxaldehyde (1) has been prepared and the aldehyde groups were subsequently protected with acetal groups to produce 1,1′-bisacetalferrocene (2). A ring-locked ferrocene was synthesised by further derivatisation of the cyclopentadiene rings at the 2,2′ positions with phosphine substituents to produce 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene (3), which was subsequently coordinated to either a nickel chloride (5) or nickel bromide (6) metal centre. The ring-locked ferrocene complexes produced 2,5′-bis-(acetal)-1,1′-diphenylphosphinoferrocene substitution patterns. The acetal protecting groups of 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene were removed to produce 1,1′-bis-carboxaldehyde-2,2′-diphenylphosphinoferrocene (4). The Cp rings of 1,1′-bisacetalferrocene were also further derivatised at the 2,2′ positions with a silane to produce the ring-locked 1,1′-siloxane-2,5′-bisacetalferrocenophane (7). The acetal protecting groups were removed from this to produce 1,1′-siloxane-2,5′-ferrocenophanecarboxaldehyde (8). For both the phosphine and siloxane electrophiles, the substitution on the Cp rings gives chiral products (obtained as racemic mixtures). Due to the highly regioselective nature of the reaction and diastereoselectivity in the products only C₂-symmetric compounds were observed without the presence of meso diastereoisomers. Subsequent ring-locking forced the Cp rings to rotate, leading to 1,1′-ring-locked ferrocenes with 2,5′-arrangement of the acetal groups (i.e. on opposite faces of the ferrocene unit).     

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.     

1,1′-Methylene-bis(1,1′,2,2′,3,3′,4,4′-octahydroisoquinoline): synthesis, reaction, resolution, and application in catalytic enantioselective transformations

The preparation of new chiral 1,3-diamine ligand systems based on the 1,1′-methylene-bis(1,1′,2,2′,3,3′,4,4′-octahydroisoquinoline) framework is described. Synthesis of various mono-, di-, and bridged N-alkyl derivatives are presented. Resolution of one compound, its Cu(I)Br X-ray crystallographic structure and the preliminary results on its application in the enantioselective Henry and Aldol reactions are disclosed.     

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.     

Facile acid-catalyzed condensation of 2-hydroxy-2,2′-biindan-1,1′,3,3′-tetrone with phenols, methoxyaromatic systems and enols

Various phenols, methoxy aromatic compounds, 3- and 4-hydroxycoumarins and enols smoothly condense with 2-hydroxy-2,2′-biindan-1,1′,3,3′-tetrone 1 in an acid medium producing 2-aryl/alkyl-2,2′-biindan-1,1′,3,3′-tetrones in high yields. The adducts of resorcinol, 1,3,5-trihydroxybenzene and α- and β-naphthols of 1 preferably remain in the intramolecular hemi-ketal form, confirmed by X-ray diffraction studies. On the other hand para and meta substituted phenols condense with 1 in an acid medium to produce 6 or 7 substituted 2′,4-spiro(1′,3′-indanedion)-indeno[3,2-b]chromenes in good yields.     

A facile synthesis of fused aromatic spiroacetals based on the 3,4,3′,4′-tetrahydro-2,2′-spirobis(2H-1-benzopyran) skeleton

The facile synthesis of a series of aromatic 6,6-spiroacetals based on the parent 3,4,3′,4′-tetrahydro-2,2′-spirobis(2H-1-benzopyran) heterocyclic system is reported. Key steps included the use of a Sonogashira coupling for the synthesis of an aryl acetylene that was coupled to an aryl aldehyde to form a propargyl alcohol intermediate. Hydrogenation of the alkynol followed by oxidation produced a masked dihydroxy ketone that upon treatment with trimethylsilyl bromide underwent deprotection and cyclisation to the fused aromatic spiroacetal.     

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.     

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.     

Facile synthesis of chiral 2-formyl-1,1′-binaphthyl via lipase-catalyzed acylation and hydrolysis of 1,1′-binaphthyl oximes

Lipase-catalyzed acylation of 2-hydroxyiminomethyl-1,1′-binaphthyl [(±)-1] and hydrolysis of 2-acetoxyiminomethyl-1,1′-binaphthyl [(±)-2] yielded optically active oximes 1 and 2 with high enantiomeric excess. Successful synthesis of the optically active aldehyde 4 from chiral O-acetyl oxime 2 occurred without a decrease of enantiomeric excess.     

A simple synthetic approach to homochiral 6- and 6′-substituted 1,1′-binaphthyl derivatives

Various homochiral binaphthyl derivatives having functional groups at the 6-position are important key intermediates for the immobilization of binaphthyl compounds on various solid-supports and have been prepared from commercially available 1,1′-bi-2-naphthol via controlled monopivalation of the 2-hydroxyl group and electrophilic aromatic substitution at the 6-position. (S)-2,2′-Bis-((S)-4-alkyloxazol-2-yl)-6-(2-methoxycarbonyl)ethyl-1,1′-binaphthyls (6-functionalized (S,S)-boxax)) were prepared and immobilized on various polymer supports including PS-PEG, PS, PEGA and MeO-PEG resin.     

Synthesis of extended ethynylnaphthalene-based ruthenium(II) 2,2′:6′,2″-terpyridine complexes

A ‘synthesis-at-metal’ approach is described for the preparation of extended ethynylnaphthalene-based ruthenium(II) 2,2′:6′,2″-terpyridine complexes.     

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.     

Synthesis of 3,3′-disubstituted-2,2′-biindolyls through sequential palladium-catalysed reactions of 2,2,2-trifluoro-N-(2-(4-[2,2,2-trifluoro-acetylamino)-phenyl]-buta-1,3-diynyl)-phenyl)-acetamide with organic halides/triflates

Palladium-catalysed reactions of aryl iodides/vinyl triflates with 2,2,2-trifluoro-N-(2-(4-[2,2,2-trifluoro-acetylamino)-phenyl]-buta-1,3-diynyl)-phenyl)-acetamide provide a straightforward entry into 3,3′-disubstituted-2,2′-biindolyls. Subsequent application of the procedure to homochiral aryl iodides affords the corresponding chiral 3,3′-disubstituted-2,2′-biindolyls. The methodology can also be applied to the synthesis of benzo[c]indolo[2,3-a]carbazoles.     

Acid-catalyzed condensation of 2,2′-diamino-1,1′-biaryls for the synthesis of benzo[c]carbazoles

2,2′-Diamino-1,1′-biaryls were found to undergo ring-closure condensation reaction to afford benzo[c]carbazoles in good to excellent yield. Coupled with the synthesis of 2,2′-biaryldiamines from diaryl hydrazides via [3,3]-sigmatropic rearrangement, it constitutes a new efficient synthetic method for benzo[c]carbazoles and related compounds.     

(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.     

Synthesis and structural investigation of 1′,3′,3′-trimethyl-6-hydroxy-spiro(2H-1-benzopyran-2,2′-indoline), 1′,3′,3′-trimethyl-6-methacryloyloxy-spiro(2H-1-benzopyran-2,2′-indoline) and a copolymer with methyl methacrylate by 1D and 2D NMR spectroscopy

Photo-responsive spiropyran-based compounds, such as, 1′,3′,3′-trimethyl-6-hydroxy-spiro(2H-1-benzopyran-2,2′-indoline) [OHSP], its monomer, such as 1′,3′,3′-trimethyl-6-methacryloyloxy-spiro(2H-1-benzopyran-2,2′-indoline) [MOSP] and its copolymers with methyl methacrylate [MMA] were synthesised using conventional synthetic routes. The copolymerisation was carried out either in tetrahydrofuran [THF] or in toluene using 2,2′-azobisisobutyronitrile [AIBN] as an initiator. The structures of these materials were investigated using ¹H and ¹³C NMR spectroscopy. DEPT-135, HCCOSW and COSY45 NMR experiments were used to assign and interpret the complex structure of spiropyran based materials.