Naphthols, synthesis

Cycloaddition of the carbene chromium complexes 97 with CO incorporation provides a versatile method for naphthol synthesis, in which the metallacy-clic intermediates 99 are involved [47]. An alternative entry to 101 is achieved by metal carbonyl-catalyzed rearrangement of the cyclopropenes 98 via the same metalla-cyclobutenes 99 and vinylketene complexes 100 [52], Mo(CO)6 shows a higher activity than Cr(CO)6 and W(CO)6. The vinylketene complex 103 is formed by the regioselective ring cleavage of 1,3,3-trimethylcyelopropene 102 with an excess of Fe2(CO)9 [53]. (Scheme 35 and 36)... 

Fig. 5.24. Regioselective azo coupling between diazotized sulfanilic acid and sodium 1-naphtholate (synthesis of Orange I).

Fiedorow, R Pasikowska, M. Koroniak, H. Mazurkiewicz, R. Zawadiak, J. Orlinska, B. Stec, Z. Grymel, M. Rearrangements of free radicals during 2-naphthol synthesis from 2-isopropylnaphtha-lene. Theochemlfm, 758, 75-79. 

Figure 6 summarizes the preparation of key iatermediates from beazeae, and Figure 7 shows a dye synthesis from benzene. Figures 8 and 9 show the preparation of key iatermediates from aaphthaleae and P-naphthol. 

Naphtho[2,3-h]indolizine-6,l 1-dione, 1, 337 Naphthoisocoumarin synthesis, 3, 831, 832 Naphtho[l,2-c]isothiazole, 3-amino-synthesis, 5, 136 2-Naphthol, l-(2-thiazolylazo)-analytical uses, 6, 328 Naphtholactam, 1, 326 Naphtholactone dyes, 1, 326... 

The historieal aspeets of synthesis, study and applieation of heteroeyelie azoeompounds (HAC) pyridynie of a line in airalytieal ehemistry are eonsidered. Works of A.E. Chieibabin on diazotation of 2-aminopyridine and it azoeopulation with resoreinol (PAR) and 2-naphthol (PAN-2). 

BUCHERER LE PETIT Naphthol (Naphihylamine) Synthesis Synthesis of naphihylamines tram naphthols and naphihols from naphthylamines... 

Two different all-aromatic crowns have been reported ". In 1975, de Jong, Siegel and Cram reported the synthesis of a tri-binaphthyl system in which each oxygen was bound to a naphthalene ring, but aliphatic bridges were used to join the binaphthyl units. Relatives of this compound are discussed further in Sect. 3.13. The synthesis of this molecule (Structure 17, below) was not simple, but was relatively straightforward. An interesting feature of it was the use of ethyl chloroacetate followed by LAH reduction to attach ethyleneoxy units to the naphthol unit. 

The Bucherer carbazole synthesis was first demonstrated when 7 was heated in the presence of phenylhydrazines 8, sodium hydroxide and sodium bisulfite after acidic work-up, the benzocarbazole product 9 was isolated (-70% yield). When 2-naphthol was used the reaction was significantly slower with the yield of benzocarbazole being only 46% after several days at 130 °C Bucherer and co-workers investigated this reaction extensively concluding, incorrectly, that intermediate products were probably carbazole-Al-sulfonic acids due to the ease with which they lost the sulfonic acid residues to yield benzocarbazoles. 

The Bucherer carbazole synthesis is, to a certain extent, limited by the availabilty of the starting naphthol and naphthylamine reagents. However, a variety of substituents have been used and these are illustrated for the conversion of 25 to 27. The use of 2-aminoanthracene in the Bucherer carbazole synthesis has also been demonstrated."... 

Chemists working with azo dyes use a shorthand designation based on the synthesis by azo coupling. It is characterized by an arrow from the amine used for diazotization (the so-called diazo component) to the coupling component, e. g., for 1.8 sulfanilic acid - 2-naphthol. This designation is especially useful for polyazo dyes (see Zollinger, 1991, p. 109). 

Although benzobarrelene has been used in a number of recent studies, the best available published synthesis" starts with the Diels-Alder reaction of j8-naphthol and maleic anhydride, affording benzobarrelene in ca. 1% yield after five further steps. Minor improvements allow small quantities of benzobarrelene to be prepared in an overall yield of ca. 10%. The reaction of benzyne with benzene is relatively inefficient, giving benzobarrelene in ca. 2% yield. When benzyne is generated by decomposition of benzenediazonium-2-carboxylate at high dilution in benzene, the yield of benzobarrelene is raised to 14%. The reactions of benzyne with other aromatic substrates are equally inefficient. 

In recent years, axially chiral binaphthalene derivatives have emerged as important ligands and chiraUty inducers in organic synthesis. Oxidative coupling of 2-naphthols represents a well estabhshed method for the preparation of binaphthols. The couplings are usually carried out by treating naphthols with more than an equimolar amount of a metal such as Fe(III), Mn(III),... 

Organic synthesis 35 [OS 35] Formation of 1-(phenylazo)-2-naphthol (Sudan I) [4]... 

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