Phenols thiophenols

Sjwyer and coworkers have developed an efficient alternative UUmann synthesis of diaryl ethers, diaryl thioethers, and diarylamines using the SnAt reaction. Phenol, thiophenol, or aniline reacts v/ith an appropriate aryl halide, In the presence of KF-aliunina and 18-crovm-6 In acetonitrile or DMSO to give the corresponding diaryl ether or diaryl thio ether as shovm In Eqs. 9.6 and 9.7. ... 

The relative rates of reaction of the silene Me2Si=C(SiMe3)2 with a series of amines, alcohols, phenols, thiophenols, dienes, and alkenes were obtained174 and are reported in Table VIII Section IV.C. 

Vogtle has developed this approach further and employed a series of anionic templates to prepare rotaxanes (instead of the neutral template in the above reaction) [65-67]. In this approach a phenolate, thiophenolate or sulfonamide anion is non-covalently bound to the tetralactam macrocycle (46) forming a host-guest complex via hydrogen bonding (see Scheme 21). 

Acid halides react with vinylphosphoranes (56) to afford isolable N-acylaminophosphonium salts (57), which are hydrolyzed by alkali to N-vinylamides (58). By treatment with triethylamine and phenol the halogen in 57 can be nucleophilically exchanged for phenolate. Thiophenol, secondary amines, and hydrazones can be employed instead of phenol this leads to diverse 1-hetero-substituted 2-aza-1,3-dienes 59 (Scheme 31) (90TL3497). 

With sulfur and triethylamine in dimethylformamide, compounds (86) give (89) (Equation (21)) <89JPR243>. With thiols or KjS, sulfides are produced (e.g., (90) and (91)), which show spasmolytic activity in vitro <86MI 404-01 >. Smooth 5N2-displacements of chlorine occur with phenol, thiophenol, SCN, and thiourea in dimethylsulfoxide. However, with K2CO3 or sodium cyanide, (86) (Ar = Ph) affords the trimers (92) or (93) (Scheme 32). With electron-deficient trans alkenes, stereoselective formation of cyclopropanes (94) was observed (Scheme 32). No reactions occur with maleates <66HCA412>. 

Fluoroboric acid supported on silica (HBF4-silica) has recently been found to be a highly efficient catalyst in the protection of various functional groups. Structurally diverse alcohols, phenols, thiophenols, and anilines can be acylated under solvent-free conditions at room temperature.669 Even acid-sensitive tertiary alcohols (1-alkylcyclo-hexanols) and sterically hindered compounds, such as endo-borneol, give the acylated products in high yields. A triflic acid-silica catalyst also shows high activity in the (9-acetylation with Ac20 of alcohols and phenols.359... 

Reaction of 2-chloro-6H-pyrido[l,2-fc]pyridazin-6-ones 14 with phenols, thiophenols, 2,4-difluorobenzyl zinc bromide, biphen-2-ylboronic acid, 2,4-difluoroaniline, and NH4OH/NH4CI afforded different 2-substituted 6H-pyrido[l,2-fc]pyridazin-6-ones 15-20 (Scheme 1) (07USA2007/... 

GC analysis of underivatized polar fractions did not reveal any volatile sulfur compounds. However, once these fractions were methylated with diazomethane, a number of sulfur compounds were detected. (Presumably, the diazomethane methylated either carboxylic acid, phenolic, thiophenolic, sulfonic acid or even alcohol or thiol groups and thereby increased their parent molecules volatility). These additional sulfur compounds are currently under investigation in our laboratories and the results of these studies will be reported later. 

SCHEME 82. Reactivities of the monomer (M) and of dimer (D) of LiSIPB with benzoyl substituted phenol, thiophenol and, imidazole and the possible transition state model for the benzoate392... 

Thiophene sulfonium salts have also been used for alkylation of phenols, thiophenols, and other nucleophiles (Equation 70) <2001T2871>. Ylides generated from THT and alkyl or allyl halides are known to react with aldehydes to form oxiranes. However, a modified procedure has been developed in which only a catalytic amount of THT is used for the preparation of vinyloxiranes from allyl bromides and aldehydes. In most of the cases, a m-/ra r-mixture of vinyloxiranes was obtained. Optically pure C2-symmetric /ra r-2,5-dimethyltetrahydrothiophene has also been used for the asymmetric version of this reaction, but the enantioselectivity was poor (25% ee) (Equation 71) <2003CC2074>. 

Fujio et al., unpublished), elimination reactions of p-arylethyl halides and tosylates (Tsuno, 1974 Fujio el al., unpublished), the phenyl ester hydrolyses (Ryan and Humffray, 1966, 1967 Humffray and Ryan, 1967, 1969), pK, values of phenols, thiophenols, anilinium ions and dimethylanilinium ions (Yukawa et al., 1966 Tsuno, 1974) and pK, values of sulphonanilides (Yoshioka et al., 1962). All these correlations are not directly related to the systems involved in the present review and they will be reviewed separately elsewhere. 

In principle other halogens apart from iodide may also be used as a promoter. For bromide, Monsanto reports the synthesis of propionic acid from ethylene with selectivities of more than 99 % when a large excess of bromide in the form of hy-drobromic acid is added to a rhodium catalyst [21]. The carbonylation is catalytic both with respect to the rhodium and the bromide components. Nonhalogen promoters in combination with rhodium as catalyst are phenols, thiophenols, thiocar-boxylic acids, and sulfonic acids [22]. 

However, the substituents shown in the lefthand column hinder the oxidation of the toluene derivatives completely. Phenols, thiophenols, anilines, o-phenoxy-, and iodine-substituted arenes cannot be oxidized to the aromatic acids, for these substituents act as strong radical scavengers and thus as catalyst and autoxidation poisons. In contrast to m- and p-nitrotoluene, which can be smoothly oxidized to the nitro-substituted benzoic acids, o-nitrotoluene and its derivatives turned out be almost inert. This is due to the high reactivity of the benzylic radical, which ob-... 

In the standard form of this route, a carboxylic acid is heated with the orffto-disubstituted benzene orf/to-amino-phenol, -thiophenol or -aniline. An iminoether will react at a much lower temperature and iminochlorides, generated in situ using the acid, triphenylphosphine and hot carbon tetrachloride, can be used for benzimidazole or benzoxazole synthesis. Orthoesters with a KSF clay is a highly recommended variant and can be used for the synthesis of all three unsubstituted benzo-l,3-azoles. ... 

The relationship between A log values for phenol, thiophenol, and anilinium ion are shown in Figure 38. In this figure, curve I is a plot... 

Heteroatom allylation. Diisobutyl telluride is a good leaving group therefore phenols, thiophenols, and anilines are readily allylated by this salt. 

Indole-1-carboxylic acid can be converted by treatment with a carbodiimide to the anhydride (413), which can undergo reaction with amines or the sodium salts of phenols, thiophenols, pyrroles, and indoles. For example, it reacts with the sodium salt of pyrrole-2-carbaldehyde to give the product (414) (Scheme 143) <87JOC3934>. V-Chloroformylcarbazole (415), prepared by the reaction of carbazole with phosgene, has been used effectively for the fluorogenic labeling of amino acids (Equation (118)) <90TL1455>. 

Metallic complexes based on Ni, Co, and substituted phenols, thiophenols, dithiocarbamates, or phosphates are used. Typical representatives are nickel-di-butyldithiocarbamate, n-butylamin-nickel-2,2 -thio-bis-(4-terf-octyl-phenolate), nickel-bis-[2,2 -thio-bis-(4-rcri-octyl-phenolate)] and nickel-(0-ethyl-3,5-di-terf-butyl-4-hydroxy-benzyl)-phosphonate. But their use is not as widespread as for other UV absorbers because they tend to be green. 

Alkoxyisocyanates. Methanol and 4-5 drops of triethylamine added to a soln. of startg. carbodiimide in benzene, heated at 80" for 8-10 h, and worked up after removal of the corresponding amide (Y 86-92%) at 5-10° - product. Y 58%. F.e. and nucleophiles (phenols, thiophenols, imines), also reaction with water and /cr/-butyl-amine, s. M.V. Vovk et al., Zh. Org. Khim. 24, 727-32 (1988) 1,1-acoxyisocyanates s. ibid. 1237-40. 

A second class of reactions which takes place with 2-oxazolines can be considered as ring-opening additions of phenols, thiophenols, and carboxylic acids. When these reactions are performed with bis(2-oxazoline)s and bifunctional compounds containing labile hydrogens, they give rise to ring-opening... 

Substituted naphtho[lr]furans and benzo[fc]furans were easily accessible by treatment of naphthols/substituted phenols with nitroallylic acetates through a substitution-elimination process promoted by cesium carbonate (13CEJ4344). Aminobenzo[l)]furan could be obtained by a one-pot con-densation-cyclization sequence from ethyl glycolate with chloropyridine (13BMCL2781). An intramolecular cyclization of 2-(gem-dibromovinyl) phenols(thiophenols) produced 2-bromobenzo[lr]furans(thiophenes) in the presence of Cu (13OBC4095). 

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