Naphth aldehyde

Organomagnesium compounds react with imines, prepared from 3-methoxy-2-naphth-aldehydes by a 1.4-addition mechanism. This reaction can be performed with high diastere-oselectivity. The method was applied for the synthesis of optically pure S-tetralones . Vinyhnagnesium bromide reacts as an acceptor with a ketone dimethyl hydrazone zincate 207, yielding a 1,1-bimetallic species, which can be reacted sequentially with two different electrophiles (equations 131 and 132) . The reaction proceeds via a metalla-aza-Claisen rearrangement, where the dimethylhydrazone anion behaves as an aza-allylic system . 

The authors then prepared a small library of compounds by sequentially substituting different aldehydes in the reaction. Reaction of 2-nitrobenzyl(tri-phenylphosphonium) bromide 21 with 3-benzyloxybenzaldehyde 23, 2-naphth-aldehyde 24 and 5-nitrothiophene-2-carboxaldehyde 25 produced stilbenes 26-28 in 55%, 47% and 54% overall conversion, respectively (Fig. 14.7). These results show that for a series of aromatic aldehydes of comparable reactivity, the products are obtained in similar conversions, which demonstrates the versatility of the methodology for the preparation of larger libraries of compounds. 

Observations of reactions of the present type with compounds in which the aryl groups are separated by conjugated polyenes date back to 1962.139 There have been several further reports of the process, and Leznoff and co-workers have described the reaction of 1-formylphenyl-4-phenylbuta-l,3-dienes. 140>141 The reaction does not occur with acetyl or nitro-substituents on such compounds since the lowest transition is nrr, but from l-(p-formylphenyl)-4-phenylbuta-l, 3-diene, for example, 1 -(p-formylphenyl)naphthalene and 8-phenyl-2-naphth-aldehyde are formed similar results have been reported for the /w-formylphenyl 134 ... 

Further supporting evidence is adduced from the observation that the anils of 2 -methoxy- 1-naphthaldehyde and 2-hydroxy-3-naphth-aldehyde show no marked spectral sensitivity to temperature, polarity... 

Acetaldehyde 83>, chloral 84>, isovaleralde-hyde 83)f benzaldehyde 83,100,128,140) >-isopropylbenzaldehyde 1S°J, anisaldehyde 84,loo) 2,4-dimethoxybenzaldehyde 150>, sahcylaldehyde 84>, furfural 84>, p-chlorobenz-aldehyde 14 >, phthalaldehyde 10 ), isoph-thalaldehyde 10 >, terephthalaldehyde 106>, cinnamaldehyde 84>, 2-methoxy-l-naphth-aldehyde 150>, 2-formylquinoline 105>, 9-anthraldehyde 105>, 3-pyrenealdehyde 10 > p-tolualdehyde 172>, p-nitrobenzaldehyde l72>, m-nitrobenzaldehyde 172>, />-cyanobenzaldehyde 172>... 

Verbindung C12H10N2O3 aus Naphth aldehyd-(l)-carDon8 ure-(8) 10, 746. Verbindung CigHjoNgOg aus Phenyl hydrazono-y-valerolaoton-y-carbonsaure 18, 453. 

Experiments to synthesize six membered heterocycles starting from both l,3-diphenyl-2-propanone phenylhydrazone and 2-ethoxy-l-naphth-aldehyde semicarbazone, which are unable to form five membered rings, faded [692]. 

Abstract 2,4-Disubstituted-3,4-dihydro-2/f-naphth[2,l-e][l,3]oxazines were prepared through the ring-closure reactions of the starting aminonaphthols with substituted aromatic and hetaryl aldehydes. 

Substituted amino naphthols were synthesized with reactions of 1-naphthols and the appropriate aldehydes. Some new 2,4-disubstituted-3,4-dihydro-2/f-naphth [i,2-e][i,i]oxazines that are expected to show biological activities were obtained by the ring-closure reactions with these aminonaphthols and various aldehydes. In addition, substituted-1,3-amino-hydroxy compounds, 2, can be used in chiral ligands synthesis. 

When 2-amino-l,4-naphthoquinone 492 was reacted with aliphatic aldehydes in the presence of a catalytic amount of TEA, the opposite diastereoselectivity of the reaction was reported. Except for the unsubstituted compound (R = H), the product proved to be a mixture of the diastereomers of l,4-dihydro-2//-naphth[2,3-rf [l,3]oxazine-5,10-diones in which the /ra r-isomer 495 was the predominant component (Equation 57). A slight tendency could be observed for increasing bulkiness of the substituent R to favor a higher proportion of the m-isomer 494 in the diastereomeric mixture <2003MI51>. 

Lamaty and collaborators have carried out solvent-free synthesis of nitrones in a ball mill [43]. Equimolar amounts of various aldehydes and A -substituted-hydrox-ylamines were used in conjunction with sodium bicarbonate (Scheme 3.64). For stoichiometric reaction between benzaldehyde and AT-methylhydroxylamine hydrochloride, small amount of dichloromethane was used. This reaction proceeded as a one-step condensation to give the corresponding nitrones in nearly quantitative yields, without the need to exclude air and moisture, in a shorter reaction time than by classical methods, but with comparable yields, where excess of reagents under inert atmosphere are reacted at room temperature or under heating for 1 or 2days (selected results. Table 3.32). Furthermore, the F,Z-isomeric ratio of the products obtained in ball-milling conditions were identical to those already reported in literature all the nitrones were in the more stable Z-form, with the exception of A -(naphth-2-ylmethylidene) methylamine A -oxide, known to be in the F-form. Microwave-assisted reactions gave lower yields than ball mill. 

Following the sequence seen before, two PingFer diphosphines were prepared from 150 in 90% yield. For R = o-An the diastereoselectivity was complete but for R= 1-Naphth a mixture with 80% de was formed although the major diastereomer could be purified by recrystallisation. The selectivity was explained by the formation of a phosphonium salt intermediate. The other route, starting from 151, was employed to determine the absolute configuration of the products, but is synthetically inferior because it is longer and the diastereoselectivity of aldehydes 152 is lower. " In spite of that, Ozawa and co-workers " used this aldehyde to prepare the phosphaalkene phosphine 153 in 94% yield. 

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]. 

With phenyl and naphth>l isocyanates only liquid derivatives were obtained. No diphenylurethane was formed. Jqdging by the Cfdour, oxidation with Beckmann s mixture appears to give rise to an aldehyde. 

The aldehyde obtained may be transferred to a Iqt-droxy group by - hydrogenation (in case of a fatty acid as starting material, a branched hydroxy fatty acid results) or oxidized by air or oxygen at 20-25 °C with calcium acetate or manganese naphthe-nate as a catalyst to the desired dicarboxylic acid. In protonic solvents (water or methanol), h. yields the acid or their ester directly. 

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