2-naphthyl aldehyde

Gross and Mirsch found that reaction of aromatics with dichloro methyl methyl sulfide and aluminum chloride yield aromatic aldehydes. However, the yields were lower compared to using dichloromethyl ethers as formylating agent. Cumene aldehyde was obtained in a 41%, mesityl aldehyde in 49% and 2-naphthyl aldehyde in 52% yield (Eq 1.16). 

When the aldehyde group is directly attached to a carbon atom of a ring system, the suffix -carbaldehyde is added to the name of the ring system, e.g., 2-naphthalenecarbaldehyde. When the aldehyde group is separated from the ring by a chain of carbon atoms, the compound is named (1) as a derivative of the acyclic system or (2) by conjunctive nomenclature, for example, (1) (2-naphthyl)propionaldehyde or (2) 2-naphthalenepropionaldehyde. 

Oxidation of LLDPE starts at temperatures above 150°C. This reaction produces hydroxyl and carboxyl groups in polymer molecules as well as low molecular weight compounds such as water, aldehydes, ketones, and alcohols. Oxidation reactions can occur during LLDPE pelletization and processing to protect molten resins from oxygen attack during these operations, antioxidants (radical inhibitors) must be used. These antioxidants (qv) are added to LLDPE resins in concentrations of 0.1—0.5 wt %, and maybe naphthyl amines or phenylenediamines, substituted phenols, quinones, and alkyl phosphites (4), although inhibitors based on hindered phenols are preferred. 

Meyers has demonstrated that chiral oxazolines derived from valine or rert-leucine are also effective auxiliaries for asymmetric additions to naphthalene. These chiral oxazolines (39 and 40) are more readily available than the methoxymethyl substituted compounds (3) described above but provide comparable yields and stereoselectivities in the tandem alkylation reactions. For example, addition of -butyllithium to naphthyl oxazoline 39 followed by treatment of the resulting anion with iodomethane afforded 41 in 99% yield as a 99 1 mixture of diastereomers. The identical transformation of valine derived substrate 40 led to a 97% yield of 42 with 94% de. As described above, sequential treatment of the oxazoline products 41 and 42 with MeOTf, NaBKi and aqueous oxalic acid afforded aldehydes 43 in > 98% ee and 90% ee, respectively. These experiments demonstrate that a chelating (methoxymethyl) group is not necessary for reactions to proceed with high asymmetric induction. 

By oxidation this alcohol yields perillic aldehyde which forms a semi-carbazone, melting at 199° to 200°, and perillic acid, melting at 130° to 131°. It also yields a naphthyl-urethane, melting at 146° to 147°. 

The naphthyl derived ligand, (5)-1-mcthyl-2-[(l-naphthylamino)methyl]pyrrolidine (4) is especially effective in the stereoselective additions of (Z)-l-cthylthio-l-trimethylsilyloxy-l-propene to aldehydes. Thus, quantitative formation of. yyn-adducts is achieved, in addition to high reagent-induced stereoselectivity (>98% ee for the 3-hydroxy thioester products)23 32. 

The proline derived diamines 2 and 4 (vide supra) are also suitable chiral additives in enantiose-lective additions of a-unsubstituted enolates. Best results are obtained with the naphthyl derivative, as demonstrated in the tin(II) triflate mediated addition of the O-silylketene thio-acetal l-toT-butylthio-l-trimethylsilyloxyethane to aldehydes which delivers 3-hydroxythio esters in optical purities of up to 95% ee and chemical yields between 50 and 90 %24... 

Chiral imines derived from 1-phenylethanone and (I. Sj-exo-l, 7,7-trimethyIbicyclo-[2.2.1]heptan-2-amine [(S)-isobornylamine], (.S>1-phenylethanamine or (R)-l-(1-naphthyl) ethanamine are transformed into the corresponding (vinylamino)dichloroboranes (e.g., 3) by treatment with trichloroborane and triethylamine in dichloromethane. Reaction of the chiral boron azaenolates with aromatic aldehydes at 25 "C, and subsequent acidic hydrolysis, furnishes aldol adducts with enantiomeric excesses in the range of 2.5 to 47.7%. Significantly lower asymmetric inductions are obtained from additions of the corresponding lithium and magnesium azaenolates. Best results arc achieved using (.S )-isobornylamine as the chiral auxiliary 3. 

An attractive alternative to these novel aminoalcohol type modifiers is the use of 1-(1-naphthyl)ethylamine (NEA, Fig. 5) and derivatives thereof as chiral modifiers [45-47]. Trace quantities of (R)- or (S)-l-(l-naphthyl)ethylamine induce up to 82% ee in the hydrogenation of ethyl pyruvate over Pt/alumina. Note that naphthylethylamine is only a precursor of the actual modifier, which is formed in situ by reductive alkylation of NEA with the reactant ethyl pyruvate. This transformation (Fig. 5), which proceeds via imine formation and subsequent reduction of the C=N bond, is highly diastereoselective (d.e. >95%). Reductive alkylation of NEA with different aldehydes or ketones provides easy access to a variety of related modifiers [47]. The enantioselection occurring with the modifiers derived from NEA could be rationalized with the same strategy of molecular modelling as demonstrated for the Pt-cinchona system. 

Thus, [HRh(C0)(TPPTS)3]/H20/silica (TPPTS = sodium salt of tri(m-sulfophenyl)phopshine) catalyzes the hydroformylation of heavy and functionalized olefins,118-122 the selective hydrogenation of a,/3-unsaturated aldehydes,84 and the asymmetric hydrogenation of 2-(6 -methoxy-2 -naphthyl)acrylic add (a precursor of naproxen).123,124 More recently, this methodology was tested for the palladium-catalyzed Trost Tsuji (allylic substitution) and Heck (olefin arylation) reactions.125-127... 

Zhang and Chan122 found that Hg-BINOL, (R)- or (S )-134, in which the naphthyl rings in the BINOL were partially hydrogenated,123 can give even better results in the diethylzinc reactions. Using (R)- or (5,)-134 as the chiral ligand, addition of diethylzinc to aromatic aldehydes proceeds smoothly with over 95% ee and, in most cases, quantitative conversion.122... 

The asymmetric hydroformylation of aryl ethenes such as substituted styrene and substituted -naphthyl ethene will lead to the intermediates for important pharmaceuticals. Much concerted effort has been applied to achieve high enantioselectivity as well as high regioselectivity toward the branched aldehydes. The research work in this area is of great industrial interest, and it continues to be a dynamic field of study. 

A variety of benzylamines 124 (R1 = Ph, Ar, 2-naphthyl, or 3- or 4-pyridyl etc NR22 = piperidin-l-yl or morpholin-4-yl) was obtained from benzotriazole, an aldehyde R CIIO and an amine HNR22 and subsequent reduction of the products with sodium borohydride (equation 44)125. 

Molecular models suggest that the aldehyde (68, X = H) can assume a coplanar conformation with the naphthyl group, whereas such a coplanar conformation is not possible for any of the other compounds. This situation is reflected in the infrared carbonyl stretching frequencies. The ap forms of these compounds absorb generally at higher frequencies than do their sp counterparts. 

A model accounting for the observed sense of absolute stereoinduction is based upon the coordination mode revealed in the crystal structure of the cyclometallated C,0-benzoate complex [280]. It is postulated that aldehyde binding by the a-allyl haptomer occurs such that the allyl moiety is placed between the naphthyl and phenyl moieties of the hgand, allowing the aldehyde to reside in a more open enviromnent. In the favored mode of addition, the aldehyde C-H bond projects into... 

Photolysis of 2-naphthyl thioesters in the presence of a hydrogen donor such as 1,4-cyclohexadiene yields aldehydes (80-100%) no photo-Fries reaction products have been reported [60],... 

The same dendritic ligands were used for the addition of disopropylzinc and diethylzinc to aldehydes (phenyl, 2-naphthyl, / -tolyl) 46). The two ligands were equally selective for the (J )-alcohol product (77% < ee 86%, depending on the substrate). Dendrimer 53 was recovered after the reaction between diethylzinc and benzaldehyde and was reused in a consecutive run, giving the same enantioselec-tivity. 

Acetylbenzaldehyde led to the expected product with complete chemoselectivity toward the aldehyde (Table 12, entry 13). Only a moderate yield was obtained with 1-naphthyl carboxaldehyde as the substrate (Table 12, entry 14). With an... 

Table IV summarizes the pertinent characteristics of some of the naphthyl carbonyl compounds. All of these compounds emit from a it,7T triplet very similar to that of naphthalene. Those that have been studied are resistant to photoreduction in isopropyl alcohol and photocycloaddition with 2-methyl-2-butene25 and isobutylene.17 Significant oxetane formation was, however, observed with the aldehydes, albeit with only moderate efficiency (quantum yield approximately one-tenth that of benzaldehyde).25...

Some alicyclic alcohols are important as synthetic sandalwood fragrances. A few alicyclic aldehydes are valuable perfume materials and are obtained by Diels Alder reactions using terpenes and acrolein. Esters derived from hydrogenated aromatic compounds, such as /cr/-butylcyclohexyl and decahydro-/3-naphthyl acetates, are also used in large amounts as fragrance materials. 

Allen et at. found that high yields of the dissymmetric trans-2,3-diaryloxirans result from the reaction between semistabilized arsonium ylides derived from the benzyl salts of the enantiomers of racemic o-phen-ylenebismethyl phenylarsine and of methyl a-naphthyl-p-tolylarsine upon reaction with prochiral aromatic aldehydes. Optical yields of between 4.7 and 38% are obtained using optically active arsonium salts (2). 

---