1.1- Binaphthyls, formation

Tab. 5. PIFA-mediated binaphthyl formation from substituted naphthyl ethers.

Scheme 31. Proposed mechanism for both carbazole and binaphthyl formation upon exposure of naphthylamine derivatives to copper(ll) and an amine base.

Additional lack of chain flexibility is introduced in the polyphosphazene skeleton when polyspirophosphazenes are considered. These materials are obtained by reacting 2,2 -di-hydroxy biphenyl or l,r-binaphthyl derivatives with polydichlorophosphazene [305], leading to the formation of polymers having the structure shown in Formula below. 

The use of chiral C2-symmetric trifluoromethanesulfonamides derived from (i )-1,1 -binaphthyl-2,2 -diamine in similar reactions to those described above has led to the formation of the expected alcohols with enantioselectivities of 43-54% ees. Better enantioselectivities were observed by Paquette et al, resulting from the use of chiral C2-symmetric VERDI (verbenone dimers) disulfonamides derived from the dimerisation of (+ )-verbenone. Stereoselectivity levels ranging from 72 to 98% ee were observed, depending on the structural characteristics of the aldehyde (Scheme 3.45). ... 

For the lanthanide Ce(III), Eu(III), La(III) complexes being derivatives of R-2,2 -diamino-l,l -binaphthyl and 2,6-diformylpyridine, the formation of the macrocycle of D2 symmetry was suggested.113 The full assignment... 

A palladium-catalyzed protocol for carbon-sulfur bond formation between an aryl triflate and para-methoxybenzylthiol was introduced by Macmillan and Anderson (Scheme 6.66) [138], Using palladium(II) acetate as a palladium source and 2,2 -bis(diphenylphosphino)-l,l -binaphthyl (BINAP) as a ligand, microwave heating of the two starting materials in N,N-dimethylformamide at 150 °C for 20 min in the presence of triethylamine base led to the formation of the desired sulfide in 85% yield. 

Intramolecular arylation of G-H bonds gives cyclic aromatic compounds. In this intramolecular arylation, the carbon-palladium cr-bond is first formed by the oxidative addition of Pd(0) species and then the resulting electrophilic Pd(n) species undergoes the intramolecular G-H bond activation leading to the formation of the palladacycle, which finally affords the cyclic aromatic compounds via reductive elimination.87 For example, the fluoroanthene derivative is formed by the palladium-catalyzed reaction of the binaphthyl triflate, as shown in Scheme 8.88 This type of intramolecular arylation is applied to the construction of five- and six-membered carbocyclic and heterocyclic systems.89 89 89 ... 

A variety of optically active 4,4-disubstituted allenecarboxylates 245 were provided by HWE reaction of intermediate disubstituted ketene acetates 244 with homochiral HWE reagents 246 developed by Tanaka and co-workers (Scheme 4.63) [99]. a,a-Di-substituted phenyl or 2,6-di-tert-butyl-4-methylphenyl (BHT) acetates 243 were used for the formation of 245 [100]. Addition of ZnCl2 to a solution of the lithiated phos-phonate may cause binding of the rigidly chelated phosphonate anion by Zn2+, where the axially chiral binaphthyl group dictates the orientation of the approach to the electrophile from the less hindered si phase of the reagent. Similarly, the aryl phosphorus methylphosphonium salt 248 was converted to a titanium ylide, which was condensed with aromatic aldehydes to provide allenes 249 with poor ee (Scheme 4.64) [101]. 

The results obtained for ligands 48 and 50, which contain only one fixed stereocentre, are interesting and very informative about the system. Ligand 48-(R,—), in which only the binaphthyl bridge has a predetermined absolute configuration R, leads to an e.e. of 83% (R-aldehyde), which is quite close to the value of 94% for (R,S)-BINAPHOS. This suggests that in the formation of the complex the binaphthyl bridge controls the conformation of the bisphenol... 

In terms of nitration, the system (NaN02 + CF3SO3H) is of no interest. At the same time, dimerization in this system can be attractive. For the last direction, CF3SO3H (or FSO3H) is necessary to produce binaphthyl derivatives more preferentially than nitro compounds (Tanaka et al. 1996). This work was preceded by the observation that the reaction of NO+AICI4 with 1-methyl-, 1,2-dimethyl-, 1,3-dimethyl, or 1,8-dimethylnaphthalenes in liquid SO2 leads to a partial a,a-dimerization (see Borodkin et al. 1993). Ozeryanskii et al. (1998) published the dimerization of l,8-Af,Af-bis(d imethylamino)naphthalene by the action of NOj in CHCI3. This reaction is accompanied by the formation of 4-nitro-l,8-A,A-bis(dimethylamino)naphthalene. Both gronps of anthors consider cation-radicals of the initial substrates as intermediate species. 

In search of a convenient procedure for preparing diazo substrates for the cycloaddition to Cgg, Wudl introduced the base-induced decomposition of tosyl-hydrazones [116]. This procedure allows the in situ generation of the diazo compoimd without the requirement of its purification prior to addition to Cgg. Since they are rapidly trapped by the fullerene, even unstable diazo compounds can be successfully used in the 1,3-dipolar cycloaddition. In a one-pot reaction the tosyUiydrazone is converted into its anion with bases such as sodium methoxide or butylHfhium, which after decomposition readily adds to Cgg (at about 70 °C). This method was first proven to be successful with substrate 142. Some more reactions that indicate the versatility of this procedure are shown in Table 4.4. Reaction of 142 with CgQ under the previously described conditions and subsequent deprotection of the tert-butyl ester leads to [6,6]-phenyl-C5j-butyric acid (PCBA) that can easily be functionalized by esterification or amide-formation [116]. PCBA was used to obtain the already described binaphthyl-dimer (obtained from 149 by twofold addition) in a DCC-coupling reaction [122]. 

Hodgson and co-workers have studied the intramolecular cascade carbonyl ylide formation-cycloaddition with chiral Rh(ii) catalysts.After screening a series of chiral Rh(ii) catalysts, high enantioselectivity was achieved in the reaction of 98 by using the Rh(ii) catalyst with binaphthyl phosphate-derived chiral ligands dirhodium(ii) tetrakis[(i )-6,6 -didodecylbinaphtholphosphate] [Rh2(i -DDBNP)4] (Equation (13)). 

The oxidation of phenols forming aryloxyl radicals was first recognized by Pummerer and Frankfurter in 1914," who reacted 2,2 -dihydroxy-l,l -binaphthyl with ferricyanide, and isolated dimers and trimers of the radical 20 (equation 8), which was later observed by ESR." Many further examples were studied by Goldschmidt, Muller, and others," and an X-ray crystal structure confirmed dimer formation with C—O bonding at the 4-position for 3-bromo-2,4,6-triphenylphenoxyl. ... 

The formation of dimers was also observed - in the electrolysis of RMgBr solutions in EtaO with R = a-Naph (the yield of l,l -binaphthyl was 43%) and a number of Grignard reagents with R being the derivatives of terpenes. 

Phenyllithium also converts 2-benzothiopyrylium salts to stable 2-thianaphthalenes271 (isomers of 83) which possess NMR spectra resembling that of an aromatic system. Formation of l,l -dihydro-2,2 -dithia-l,l -binaphthyl (85) is possible from the one-electron reduction of 2-benzothiopyrylium salts.314... 

The Bolm protocol was recently used by Ellman et al. for the enantioselective oxidation of -butyl disulfide 22 [72], Excellent result was achieved in the formation of thiosulfinate 22 (91% ee, 93% yield) by using catalyst 20 (0.25 mol %) in a 0,5 mmol scale. In spite of extensive screening of chiral Schiff bases related to catalyst 20, better enantioselectivity was not realized. Chiral thiosulfinate 22 is a convenient starting material for the preparation of r-butyl sulfi-namides and t-butyl sulfoxides. Vetter and Berkessel modified the structure of the Schiff base moiety of catalyst 20 by replacing the aryl ring with a 1,l -binaphthyl system [73]. The corresponding vanadium catalyst realized 78% ee in the oxidation of thioanisol, which was better than that attained by the Bolm catalyst (59% ee). 

The vinylcyclopropane radical cation, generated at 77 K by X-irradiation of (139) in a Freon-113 matrix, was shown to rearrange at 105-110 K to afford two ring-opened distonic radical cationic species.300 The rearrangement reactions of the radical cations of 1,3- and 1,4-pentadiene and cyclopentene and the formation of spin adducts with 2.4.6-tri-/-butylnitrosobenzene (BNB) are discussed. The pulse radiolysis of 1,1 -binaphthyl-2,2,-diyl hydrogenphosphate (BiNPCUH) (140) in deaerated f-butanol at... 

This compound, in common with other suitable substituted biphenyls, possesses a chiral axis (p. 6) and is isolated from the reaction as a racemate. Although several resolution procedures have been reported, the superior method to date4 is that in which the binaphthol is first converted by treatment with phosphorus oxychloride into the binaphthyl phosphoric acid (14). Resolution is then effected by formation of diastereoisomeric salts with (+ )-cinchonine, appropriate fractional crystallisation and recovery of the (S)-( + )-binaphthyl phosphoric acid. Suitable hydrolysis gives (S)-( — )-l,l -bi-2-naphthol (15). 

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