Naphthols, cross-coupling

Research by Vyskocil and co-workers extended the naphthol cross-coupling reaction to mixtures of 2-naphthols and naphthylamines (Scheme 29) [85, 86]. In general, good selectivity in favor of cross-coupling over homo-coupling was observed. 

With the bisoxazoline hgand (S)-Phbox and CuCl, the asymmetric oxidative couphng of 2-naphthol and hydroxy-2-naphthoates resulted in an asymmetrically substituted 2,2 -binaphthol with ee s of up to 65% [260]. On the basis of the previous results obtained with this catalyst system, the asymmetric oxidative cross-coupling polymerization of 2,3-dihydroxynaphthalene [261] and methyl 6,6 -dihydroxy-2,2 -binaphthalene-7,7 -dicarboxylate [262] as well as the copolymerization of 6,6 -dihydroxy-2,2 -binaphthalene and dihexyl 6,6 -dihydroxy-2,2 -binaphthalene-7,7 -dicarboxylate with Cu diamine catalysts were carried out imder aerobic conditions, using O2 as the oxidant, and a cross-coupling selectivity of 99% was achieved [263]. 

Catalytic oxtoattve cross-coupling reaction of 2-naphthol dertvattves. 273... 

CATALYTIC OXIDATIVE CROSS-COUPLING REACTION OF 2-NAPHTHOL DERIVATIVES... 

Table 8.2 shows the results of the cross-coupling reaction between two differently substituted 2-naphthol derivatives using the CuCl-(5)Phbox catalyst. In conclusion, the first catalytic asymmetric oxidative coupling with a high cross-coupling selectivity was accomplished under mild conditions. 

They next studied the asymmetric oxidative polymerization of achiral 2,3-dihydroxynaphthalene (Scheme 42). The polymerization of this monomer with CuCl2-(-)-sparteine complex resulted in a low yield and gave a low molecular weight oligomer, whereas the polymerization with CuCl-(S)-Phbox quantitatively gave a polymer with Mn of 10 600-15 300. The enantioselectiv-ity attained in this polymerization, however, was estimated to be low, with 43% ee from the model reaction [169]. When vanadyl sulfate (VOSO -Phbox complex was used instead of the copper catalyst system, the enantioselectivity was improved up to 80% ee [170]. Asymmetric cross-coupling polymerization of two kinds of naphthol derivatives was also reported [171,172]. 

Few examples of cross-coupling between differently substituted 2-naphthols were known when Hovorka and co-workers investigated this reaction in more detail. Anaerobic condi-... 

Other Reagents for the Oxidative Coupling Reaction Tab. 23. Copper(ll)/amine-mediated cross-coupling of variously substituted 2-naphthol derivatives. 

Scheme 29. Selective cross-coupling of 2-naphthol (68a) and 2-naphthylamine (70a) mediated bycopper(ll) and an amine base.

In a comprehensive study of these cross-coupling reactions with 2-naphthol derivatives, and as a response to Ding s advances on the same transformation using iron reagents [57], Vyskocil and co-workers presented a rational explanation for the outcomes of the different... 

Scheme 52. Enantioselective cross-coupling of naphthols in the presence of the chiral amine sparteine and copper(ll).

Scheme 56. Enantioselective cross-coupling of 2-naphthol catalyzed by copper(ll)/sparteine.

SCHEME 143. Oxidative cross-coupling of 2-naphthol and 2-(p-hydroxyphenyl)ethanol... 

Hovorka M, Gtinrerova J, Zavada J (1990) Highly selective oxidative cross-coupling of substituted 2-naphthols a convenient approach to unsymmetrical 1, 1 -binaphthalene-2, 2 -diols. Tetrahedron Lett 31 413—416... 

Vyskocil S, Smrcina M, Lorenc M, Hanus V, Polasek M, Kocovsky P (1998) On the Novel two-phase oxidative cross-coupling of the two-component molecular crystal of 2-naphthol and 2-naphthylamine . Chem Commun 585-586... 

Oxidative cross-coupling of 2-naphthols is catalyzed by Cu(OH)Cl-TMEDA and assisted by Yb(OTf)3. Under such conditions BINOL containing a single methyl ester at C-3 is formed with >99% selectivity. ... 

Application of Suzuki cross-coupling methodology to thiophene boronates and bromo- or triflate-functionalised naphthols or naphthopyrans affords (2-thienyl)n derivatives of 3,3-diphenyl-3//-naphtho[2,l-6]pyrans (Scheme 11) <03EJO2799>. 

Three new substituted BINOL ligands, (i )-3-[4,6-bis(dimethylamino)-l,3,5-triazin-2-yl]-l,10-bi-2-naphthol (R)-(72), (i )-3,3 -bis[4,6-bis(dimethylamino)-l,3,5-triazin-2-yl]-l,10-bi-2-naphthol (R)- 73), and 2,4-bis(2,2 -dihydroxy-1,10-binaphthalen-3-yl)-6-(/i-tolyl)-l,3,5-triazine iR,R)-74), have been obtained by directed ort o-lithiation and a Suzuki cross-coupling process (Scheme 10) <2005TA3667>. The titanium complex of (R)-72 was found to be an effective catalyst in the asymmetric addition of diethylzinc to a variety of aromatic aldehydes. 

A third mechanism was found to be involved in the cross-coupling between 2-naphthol and 3-hydroxy-2-naphthoic acid mediated by the CuCl2-( )-sparteine complex where the purification of the precipitate and the mother liquor both gave rise to the same enantioenriched product (S)-3... 

Based on the previously described mechanistic details, the asymmetric cross-coupling reactions between two 2-naphthol molecules with different electronic properties can be expected, which will allow the facile production... 

Oxidative cross-coupling of two electronically-different 2-naphthols with CuCl2 in the presence of tert-butylamine Preparation of 3-methoxy carbonyl-1,1 -binaphthyl-2,2 -diol (395) [58]... 

Scheme 16 Site-selective cross-coupling of l,6-dibromo-2-naphthol...

In related work, the B-arylated, C-brominated version of benzo[e][l,2] azaborinine 28 was shown to undergo se arylation when treated with a Pd-catalyst in the presence of base, producing the 1,2-borazaro versions 29 of p-naphthol (Scheme 12) (2014JOC8339). Thirteen examples of products with the general stmcture 29 (59—98% yields) were described. Substituted benzo[e][l,2]azaborinines like 28 were also found susceptible to Ni-catalyzed reductive cross-coupling reactions (2014OL3692). 

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