Lithium naphthyl derivatives

Condensation of the alkoxynaphthyldihydrooxazoles with 2-methoxy-l-naphthyllithium, prepared by bromine-lithium exchange, did not lead to the same product as the corresponding reactions with the magnesium compound, but, unexpectedly, to a rearranged isomeric 1 -bi-naphthyl derivative with high enantiomeric excess28. 

The a- and /3-naphthyl derivatives, Compounds 24 and 25, as well as Compound 26 were prepared from the bis-tosylate (7) and the corresponding lithium diarylphosphide. 

The method has been recently improved, in collaboration with Fiisfero (Scheme 5) (36). In fact, lithium derivative of (6>naphthyl methyl sulfoxide 21 was found to provide much better stereocontrol in the condensation with A -PMP fluoroalkyl imines 15a,b,f. The resulting A -PMP naphthyl derivatives 22 were transformed into the enantiomeric (5)-P-fluoroalaninols 20 following an identical sequence of reactions, in high overall yields and stereoselectivity. Oxidation of the hydroxymethylene group, according to the method of Sharpless (37), extended the field of application of this strategy to the synthesis of enantiopure p-fluoro alanines 23. The wide scope of the NOP reaction is demonstrated by the fact that also naphthyl sulfoxides, like 22, can be successfully submitted to the reaction. 

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. 

Benzodiazepin-2-ones are converted efficiently into the 3-amino derivatives by reaction with triisopropylbenzenesulfonyl (trisyl) azide followed by reduction <96TL6685>. Imines from these amines undergo thermal or lithium catalysed cycloaddition to dipolarophiles to yield 3-spiro-pyrrolidine derivatives <96T13455>. Thus, treatment of the imine 50 (R = naphthyl) with LiBr/DBU in the presence of methyl acrylate affords 51 in high yield. 

Tri-(l-naphthyl)phosphine is cleaved by alkali metals in THF solution. " Reaction with sodium gives the naphthalene radical-ion, with lithium the perylene radical-ion, and with potassium the radical-ion (22). Hydrocarbon radical-ion formation was thought to occur via naphthalene derived from the metal naphthalenide. E.s.r. spectra of further examples of phosphorus-substituted picrylhydrazyl radicals have been reported. ... 

Diastereoselective 1,4- and 1,6-addition reactions of lithium amides to chiral naph-thyloxazolines were used by Shimano and Meyers108-110 for the synthesis of novel amino acids. For example, treatment of (S )-2-(l-naphthyl)-4-t-butyloxazoline with lithi-ated l,4-dioxa-8-azaspiro[4.5]decane and iodomethane provided the diastereomerically pure 1,4-addition product with excellent yield cleavage of the heterocyclic rings then gave the desired /3-amino acid (>99% ee/ds equation 32)108,109. In contrast to this, most acyclic lithium amides reacted with these oxazolines under 1,6-addition the products were transformed smoothly to 5-amino acid derivatives (equation 33)110. 

Amino-4-methoxy-l-methoxymethylnaphthalene 120, obtained from the chloromethyl derivative 111, is transformed into azide 121. The latter undergoes photolytic heterocyclization to the labile 5-methoxyben-zo[cd]indole 117 which, on reduction by lithium aluminium hydride followed by acetylation, is converted into the stable l-acetyI-5-methoxy-l, 2-dihydrobenzo[o/]indole 119 (R = OMe) [71JCS(C)721]. The reduction of methyl or phenyl 8-nitro-1 -naphthyl ketones by hydrogen and platinum dioxide or by iron in acetic acid leads to a mixture of products (59M634). 

Aromatic nitro compounds are comparable with pyridine derivatives in reactivity and can sometimes be aminated directly. l-(4 -Nitro-l -naphthyl)-piperidine was obtained from 1-nitronaphthalene and sodium piperidide (sodamide and piperidine).396 Nitrobenzene and the alkali derivative of carbazole397 or diphenylamine398 gave the corresponding /7-amino derivative, 9-(/7-nitrophenyl)carbazole (70%) and 4-nitrotriphenylamine (45%). Huisgen and Rist399 record the reaction of nitrobenzene with lithium piperidide. 

In addition, Schiff bases can also be applied as intermediates of quinoline formation. Thus, Schiff bases derived from 2-(trifluoromethyl) aniline and a methyl naphthone, mediated by lithium 2-(dimethylamino)-ethylamide, were used to furnish a series of substituted 2-(2-naphthyl)quinolines designed to target DNA. ... 

To improve the enantioselectivities, we then reinvestigated Hatakeyama s cinchona-derived catalyst, p-ICD, promoted MBH reaction of aldehydes with methyl vinyl ketone or (ot)-naphthyl acrylate in the presence of co-catalyst. The enantioselectivities increased in some cases, and the absolute configuration of the MBH adducts can be inverted by the use of proline or lithium... 

SisPhgBr with naphthyl lithium affords the phenyl derivative bi(nonaphenylcyclopenta-silanyl). When the perhalogenated cyclopentasilanedimers are reacted with LiAlH, about 15% of SisHio are obtained along with the expected product bi(cyclopentasilanyl), which demonstrates the remarkable sensitivity of the central Si—Si bond towards nucleophilic attack. 

The exploration of the chemistry of terphenyl derivatives of the group 3 metals is due mainly to Rabe and coworkers [13-18]. The ligands used were of the formula C6H3-2,6-Ar2 (Ar = CeHs, C6H2-2,4,6-Mc3, 1-naphthyl, or 3-MeO-C6H4). The halide complexes 1-3 could readily be obtained by simple salt metathesis from the reaction of the terphenyl lithium with anhydrous metal trichlorides MCI3 (M = Sc or Y) in THF at room temperature [13,14], The yttilum complexes 2 and 3 were isolated in moderate yield (ca. 50%) however, only a low yield of the scandium complex 1 could be obtained, most likely because of C-H bond activation as indicated by NMR spectroscopy. These metatheses reactions did not proceed in aromatic solvents or hexanes probably as a result of the low solubility of the reactants in these media. Complex 1 decomposes slowly in THF solution, while 2 and 3 are considerably more stable. 

Simple chiral allenes have been prepared by the reaction of propargylic carbamates with lithium dialkylcuprates. The diastereomeric carbamates, derived from racemic propargylic alcohols and (/ )-1-(l-naphthyl)ethyl isocyanate, are readily separated by h.p.l.c. they are then treated with lithium dialkycuprates at -78 °C, producing the allenes with enantiomeric excess up to 80% in yields of around 70% (Scheme 2). The method is claimed to be an improvement on earlier methods in that it is much simpler and gives better optical yields. 

Isocyanates and thioisocycanates equally harbor cumulated double bonds. As they combine virtually quantitatively with all kinds of organic lithium, sodium, or potassium compounds, they were much appreciated as trapping reagents in the early history of polar organometallic chemistry. Moreover, the products derived from iV-phenyl, yV-naphthyl, or A/-rer/-butyl substituted (thio)isocyanates crystallize extremely well. 

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