Resorcinol derivatives reaction synthesis

In 2011, Hartwig and coworkers reported the total synthesis of taiwaniaquinol B (55, Scheme 11.9), a member of a family of diterpenoids that are derived from the abietane skeleton [36]. A key aspect of the Hartwig synthesis of taiwaniaquinol B was the use of the iridium-catalyzed borylation reaction to accomplish the C(5) functionalization of resorcinol derivative 53. This regioselectivity for the overall bromination is complementary to that which would be obtained using a standard electrophilic aromatic substitution (EAS) reaction. In the transformation of 53 to 54, a sterically controlled borylation was first accomplished, which was then followed by treatment of the boronic ester intermediate with cupric bromide to... 

Most recently, the methods of template-directed solid-state synthesis were employed to constmct the [3]- and the [5]-ladderane. The construction involved a resorcinol derivative (5-methoxyresorcinol) as a linear template to organize pyridine-substituted polyenes for the reaction within discrete molecular assemblies in solids. The assemblies are... 

Fluoride-induced fragmentation reactions were used in two stages of a synthesis of hexahydrocannabi-nol methyl ether (144 Scheme 52). One of the phenolic hydroxy functions in the resorcinol derivative (140) was selectively liberated from the SEM ether to give the diol (141), which was converted to the bis (trimethylsilyl) ether (142). Subsequent treatment with CsF resulted in a 1,4-elimination to the o-quinone methide (143) intermediate, which underwent an intramolecular [4 -i- 2] cycloaddition to give the product in good yield. 

Discovery of the dienone-phenol rearrangement of quinol acetates has made possible the synthesis of dihydric phenols that were difficult of access by other routes. The starting materials are obtained from phenols and lead tetraacetate, and with acetic anhydride and sulfuric acid (Thiele acetylation) or with boron trifluoride in ether they give, respectively, di- and mono-acetyl derivatives of resorcinol or hydroquinone.309 When treated with lN-sodium hydroxide, 0-quinol acetates of type (1) undergo nucleophilic addition of an OH" ion, giving resorcinol derivatives (2).310 Occurrence of the reaction is considered... 

Among the photochemical reactions of aromatic compounds, the photocycloadditions are most frequently applied to the synthesis of complex polycyclic compounds [6, 9]. The [2+3] or meta photocycloaddition of aromatic compounds and alkenes is the most prominent example [10]. This transformation also demonstrates complementarities between photochemical and ground state reactions since such reactions are almost impossible using conventional activation. A [2+2] ot ortho photocycloaddition between carbocyclic aromatic compounds and alkenes is observed as well. It is often competitive with other cycloaddition modes, in particular the [2+3] mode [11]. Many of these reactions are reversible, and photostationary equilibria are involved. This reaction was much less applied to organic synthesis. Recently, it was found that an acidic reaction medium may have an influence on the outeome of the reaction. The intramolecular photocycloaddition of resorcinol derivatives such as 1 is difficult due to its reversibility (Scheme 29.1). However, in an acidic reaction medium, the cycloadducts 2a,b are protonated at the oxygen atom of the tetrahydrofuran moiety... 

The involvement of mixed-valent Rh /Rh species in the intermolecular C(sp )—H amination reaction has been further confirmed by the preparation of new complexes analogous to Rh2(esp)2 3. On one hand, the design of a resorcinol-derived ligand, that is structurally comparable to the esp ligand, has enabled the synthesis of the new complex 21 that is an active catalyst in intramolecular C(sp )—H amination. However, the redox properties of the resorcinol-based compound make the formation of a stable... 

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

The synthesis of Coumarin derivatives can be made cleaner using zeolite H-BEA and even cationic ion-exchange resin like Amberlyst-15 works. Reactions of resorcinol with acrylic/methacrylic acid, maleic anhydride and esters have been studied (Gunnewegh et al., 1996). 

Resorcinols. Condensation of this diene with the ketal of a fi- keto acid derivative results in a resorcinol with complete regiocontrol. Thus, the TiCl4-catalyzed reaction of 1 with ketal ester 2 results in the resorcinol 3 in 72% yield. However, use of the acid chloride 4 corresponding to 2 in the same reaction results in the isomeric resorcinol, methyl olivetolate (5). The regiocontrol is based on the reactiv ity order acid chloride > ketal > ester. The resorcinol 5 was used in a biomimetic synthesis of the chromene A1 -tetrahydrocannabinol (6), a component of marijuana. 

The usual method of synthesis of methoxy substituted benzaldehyde derivatives is by formylation of the methoxy substituted benzene derivatives. The formylation is generally effected by acid catalysed electrophilic substitution reactions like the Vils-meyer-Haack reaction. When resorcinol dimethylether is formylated under these conditions, the product obtained is the derivative (2) and not (7). 

A Methylamino)phenol. This derivative (15) is easily soluble in ethyl acetate, ethanol, diethyl ether, and benzene. It is also soluble in hot water, but only sparingly soluble in cold water. Industrial synthesis is by heating 3-(iV-methylamino)benzenesulfonic acid with sodium hydroxide at 200—220°C (179) or by the reaction of resorcinol with methylamine in the presence of aqueous phosphoric acid at 200°C (180). 

A A Diethylamino)phenol. This derivative (16) forms rhombic bipyramidal crystals. Industrial synthesis is analogous to the previously described synthesis of 3-(iV,iV-dimethylamino)phenol from resorcinol and diethylamine, by reaction of 3-(iV,iV-diethylamino)benzenesulfonic acid with sodium hydroxide, or by alkylation of 3-aminophenol hydrochloride with ethanol. 

The Pictet-Gams reaction was used for the synthesis of difficult accessible isoquinoline derivatives as the tri-isoquinoline artificial receptor of resorcinol. ... 

The two steps of gd synthesis are sketched in Fig. 5.2 in an aqueous (or organic) solution of resorcinol and formaldehyde (molar ratio 1 2), an addition reaction is catalyzed by sodium carbonate to form hydroxymethyl derivatives subsequently, these are interlinked by methylene (-CH2-) or methylene ether (-CH2OCH2-) bridges in endothermic condensation reactions (Al-Muhtaseb and Ritter, 2003). Historically, sodium carbonate is referred to as a catalyst, although its only role is to tune the pH value (Job et cd., 2004). 

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