P-Naphthol-a-aldehyde

P-Naphthol-a-aldehyde (p-hydroxy-a>naphthaldehyde). Proceed as for p-resorcylaldehyde except that 20 g. of p-naphthol replaces the resor-dnol. Recrystallise the crude product (20 g.) from water with the addition of a little decolourising carbon the pure aldehyde has m.p. 80-81°. 

Silica-supported Preyssler-type HPAs are foimd to be efficient catalysts for the synthesis of l,2-dihydro-l-aryl-3/f-naphth[l,2-e][l,3]oxazin-3-one derivatives in a convenient, efficient, good yield, and green reaction by condensation of P-naphthol, aromatic aldehydes, urea, and ethanol imder reflux conditions. The catalyst is recycled and reused several times (Scheme 3.11) [52]. 

An efficient and eco-friendly multicomponent one-pot synthesis of 12-ary 1-8,9,10,12-tetralrydrobenzo[a]xanthen-ll-ones was achieved by the condensation of p-naphthol, aromatic aldehydes, and cyclic 1,3 dicarbonyl compounds (Scheme 4.11) using the BAIL (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogen sulfate as a catalyst [140]. 

P-Hydroxy-a-naphthaldehyde, Equip a 1 litre three-necked flask with a separatory funnel, a mercury-sealed mechanical stirrer, and a long (double surface) reflux condenser. Place 50 g. of p-naphthol and 150 ml. of rectified spirit in the flask, start the stirrer, and rapidly add a solution of 100 g. of sodium hydroxide in 210 ml. of water. Heat the resulting solution to 70-80° on a water bath, and place 62 g. (42 ml.) of pure chloroform in the separatory funnel. Introduce the chloroform dropwise until reaction commences (indicated by the formation of a deep blue colour), remove the water bath, and continue the addition of the chloroform at such a rate that the mixture refluxes gently (about 1 5 hours). The sodium salt of the phenolic aldehyde separates near the end of the addition. Continue the stirring for a further 1 hour. Distil off the excess of chloroform and alcohol on a water bath use the apparatus shown in Fig. II, 41, 1, but retain the stirrer in the central aperture. Treat the residue, with stirring, dropwise with concentrated hydrochloric acid until... 

Albert S.C. Chan of the Hong Kong Polytechnic University reports (J. Org. Chem. 68 1589, 2003) two important transformations. The three-component (Mannich) condensation of 10 with 11 and 12 proceeds with high diastereoselectivity, to give the amino alcohol 13. Hydroboration of the alkyne 14 followed by transmetalation of the intermediate vinyl borane gives a zinc species, which under catalysis by the easily-prepared p-naphthol 13 adds to aromatic and branched aldehydes with high ee. The product allylic alcohols are useful intermediates for organic synthesis. 

Early work by Littman and Erode established that it was possible to vary the amino constituent of the Betti reaction. It has subsequently been shown that a wide variety of amines are suitable, depending on the reaction conditions. Indeed, primary and secondary aliphatic amines, aromatic amines and heteroaromatic amines have been used. For example, morpholine (17) was a suitable substrate for a Betti reaction when the reaction constituents were neat in the presence of a catalytic amount of p-toluenesulfonic acid under microwave irradiation. This reaction protocol is especially notable for its fast reaction rates, with the products obtained after only one minute of irradiation. Other useful reaction procedures to form diverse Betti bases have also been reported including the use of water as a solvent,and the addition of nonionic surfactants to the reaction mixture. In addition to variation of the amine component, a number of alternative aromatic and heteroaromatic aldehydes are suitable substrates. Finally, although most of the examples in the literature focus on 2-naphthol, a few alternatives have been reported, including the use of 8-quinolinol. ... 

Davoodnia and coworkers set up a simple and efficient procedure for the synthesis of 14-aryl-147f-dibenzo[fl, ]xanthenes using a one-pot condensation reaction of P-naphthol and aryl aldehydes catalyzed by silica gel-supported polyphosphoric acid (PPA/SiOj) (Khojastehnezhad et al, 2011). Xanthene derivatives occupy a prominent position in medicinal chemistry (Wang et al., 1997) and have been investigated for their agricultural bactericide activity (Handique and Baruah, 2002), antiinflammatory effect (Sirkecioglu et al, 1995), and antiviral activity. 

The probable mechanism for the synthesis of 2-amino-4//-chromene in the presence of a catalytic amount of STA is outlined in Scheme 3.30. It scans that STA acts as a Brpnsted acid so that it can release a proton to activate aromatic aldehyde. It can also prepare malononitrile for attack by the activated aromatic aldehyde. After condensation of aldehyde and malononitrile, P-naphthol reacts with the produced intermediate to give 2-amino-4/f-chromene as a product. 

These include the SSA-catalyzed synthesis of heterocyclic compounds such as xanthenes, coumarins, oxazoles, and so on. Xanthenes are of great therapeutic and biological interest on account of their many biological activities such as anti-inflanunatory, antiviral, antibacterial properties, and so on. Seyyed Hamzeh et al. (2008) carried out the SSA-catalyzed synthesis of aryl-14 f-dibenzo[fl,y]xanthenes from aldehydes and P-naphthol and 1,8-dioxo-octahydro-xanthenes from aldehydes and 1,3-dicarbonyl componnd such as dimedone under solvent-free conditions (Schemes 5.25, 5.26). Reactions were carried out at 80°C. Nazeruddin et al. (2011) documented an effective method for 9,10-dihydro-12-aryl-8 f-benzo[a]xanthenes-ll(12 f)-one derivatives in excellent yield and short reaction time using SSA under solvent-free conditions (Scheme 5.27). 

A range of 12-aryketrahydrobenzoxanthene-ll-ones were synthesized from aliphatic and aromatic aldehydes, P-naphthol, and dimedone promoted by thiamine hydrochloride in aqueous micellar medium (13TL6732) and from benzaldehydes, 2-hydroxy-l,4-naphthoquinone, and cyclic 1,3-dicarbonyl compounds using a catalytic amount of sulfuric acid in water or in the presence of the acidic ionic liquid [Bmim][HS04] (Scheme 83) (13SC2147). 

Based on this concept, Murthy and coworkers reported an intriguing reaction for the synthesis of amidoalkyl naph-thols under solvent-free conditions [54], As shown in Scheme 11.10, p-naphthol 69, alkyl/aryl aldehydes 53, and amides/thioureas 68 were stirred at room temperature and catalyzed by sihca sulfuric acid (SS A). The three-component reaction afforded amidoalkyl naphthols 70 in excellent yields (79-92%). 

Perumal has described a four-component sequential protocol that allows the synthesis in good yields of antitubercular 2-aryl-5-methyl-2,3-dihydro-l/f-3-pyrazolones 18 from atylhydrazines, methyl acetoacetate, aromatic aldehydes and 5-naphthol in the presence of / -TSA in water under reflux conditions [13], The reaction proceeds by an initial acid-catalyzed cyclocondensation of the hydrazine and dicarbonyl components to give pyrazolinone 19. A parallel acid-catalyzed condensation between p-naphthol and the aromatic aldehyde affords the intermediate quinone methide 20, and Michael addition of the enol form of 19 onto the exocyclic double bond of 20 furnishes the final product (Scheme 1.9). 

Amino-chromenes represent an important class of compounds being the main components of many naturally occurring products. They can be utilized as cosmetics, pigments widely [91], and potential biodegradable agrochemicals [92]. These compounds have been of interest to the medicinal chemist for many years. Hj pSlaPjWjQO, J was used successfully as an efficient catalyst in the reaction of aldehydes, malononitrile, and a- and P-naphthol for the synthesis of 4 and 5 (Scheme 3.33). 

Subba Reddy et al. [78] developed a highly efficient iodine-catalyzed methodology for the three-component couphng (3CC) of aldehydes, P-naphthol, and 1,3-di-methylbarbituric acid under solvent-free conditions affording the corresponding... 

The fused to naphthalene 1,3-oxazines 147 were also formed via the three-component reaction of aromatic aldehydes, urea, and 3-naphthol in PEG 400 under catalysis by the nanoparticular copper (15nm) (Scheme 84) [117]. PEG 200 was slightly less effective as the solvent for this reaction (147, Ar=Ph, 87% vs 93%). PEG 400 together with the catalyst demonstrated good recyclability. It should be noted that in case of replacement of p-naphthol by a-naphthol or naphthalene-2-thiol this reaction did not proceed. 

Ziarati et al. [69] developed the synthesis of compounds with pharmaceutical and biological properties. Thus, 2-aryl-5-methyl-2,3-dihydro-lH-3-pyrazolones (72) were synthesized via a four-component reaction of ethyl acetoac-etate (66), hydrazine (67), aldehyde (69), and p-naphthol (70) in water under ultrasound irradiation with a multiwave ultrasonic generator in the presence of nanoparticles of copper iodide as catalyst, using a simple preparation protocol (Scheme 17). It should be mentioned that the catalyst could be recycled and reused for five times without evidently... 

Eydroxy-5,6,7,8-tetrahydro-l-napMhaldehyde was prepared [7] by the Reimer-Tiemann reaction cn 5,6,7,8-tetrahydro- 2-naphthol. Three recrystallizations from aqueous alcohol afforded a very low yield of pure aldehyde, m.p. 86-8-87-8° (spectral sample) lit. m.p. 86-87° [7J. 

---