8- Quinolyl carbonates

A soln. of DL-phenylalanine cyclohexylamide and bis-(8-quinolyl) carbonate in methylene chloride kept overnight at 0° carbo-(8-quinoloxy)-DL-phenyl-... 

A soln. of L-alanine in 1 iV NaOH treated with ferf-butyl 8-quinolyl carbonate in dimethylformamide, and warmed 1.5 hrs. at 70° N-carbo-fert-butoxy-L-... 

Several products other than 2,2 -biaryls have been isolated following reaction of pyridines with metal catalysts. From the reaction of a-picoline with nickel-alumina, Willink and Wibaut isolated three dimethylbipyridines in addition to the 6,6 -dimethyl-2,2 -bipyridine but their structures have not been elucidated. From the reaction of quinaldine with palladium-on-carbon, Rapoport and his co-workers " obtained a by-product which they regarded as l,2-di(2-quinolyl)-ethane. From the reactions of pyridines and quinolines with degassed Raney nickel several different types of by-product have been identified. The structures and modes of formation of these compounds are of interest as they lead to a better insight into the processes occurring when pyridines interact with metal catalysts. 

In the intervening years, indoleboronic acids substituted at all indole carbon positions have found use in synthesis. For example, Claridge and co-workers employed 94 in a synthesis of isoquinoline 95 under standard Suzuki conditions in high yield [114], Compound 95 was subsequently converted to the new Pd-ligand l-methyl-2-diphenylphosphino-3-(l -iso-quinolyl)indole. 

Although the preparation has been repeated, there have been no other reports of the type of reaction, (described in 1923) in which carbazole in the presence of excess potassium hydroxide and nitrobenzene at only 50°C gave a good yield of 9-(4-nitrophenyl)-carbazole, presumably via an adduct such as 43 subsequently oxidized by excess nitrobenzene and/or air. More recent examples of N-arylation of carbazoles have involved copper catalysis in reaction of aryl halides with carbazoles. Thus, copper bronze and potassium carbonate heated with the carbazole and the appropriate aromatic halide have produced 9-(4-methoxyphenyl)- and 9-(2-tolyl)carbazoles 9-(4-phenylphenyl)carbazole, l,4-di(carbazol-9-yl)benzene, 4,4 -di(carbazol-9-yl)biphenyl, and 9-(2-pyridyl)- and 9-(2-quinolyl)carbazoles 9-[2-(2-phenylphenyl)phenyl]- and 9-[2-(4-methylphenyl)phenyl] carbazoles 9-(3-bromo-6-nitrophenyl)-, 9-[3-(carbazol-9-yl]-, 9-(2-nitrophenyl)-, 9-(4-methyl-2-nitrophenyl)-, 9-(4-methoxycarbonyl)-l-nitro-, and l-nitro-9-(4-tolyl)carbazoles 9-(2-methoxycarbonylphenyl)carbazole 9-[2- 2-... 

The cycloaddition of diazomethane to SchifT bases from heterocyclic aldehydes and anilines provides a useful route to heterocyclic substituted triazolines. Unlike olefins bearing heterocyclic substituents, the heterocyclic imines can be obtained readily by reaction of the appropriate aldehyde and amine thus the diazomethane-imine addition has greater scope than the olefin-azide reaction. NMR spectroscopic studies of the orientation of addition are in accord with previously reported mechanistic considerations (see, e.g., Scheme 93).329 In addition to the influence of the N-aryl group, the electron-withdrawing power of the heterocyclic substituent on the Schiff-base carbon also has a substantial effect on imine reactivity, in the order 2-quinolyl 2-, 3-, or 4-pyridyl > phenyl > 2-thienyl as 2-furyl.329... 

The anions of Reissert compounds 19 and 20 undergo reaction with aldehydes to form esters of secondary alcohols containing the 2-quinolyl or 1-isoquinolyl group bonded to the carbinol carbon atom. Thus benzaldehyde, l-benzoyl-l,2-dihydroquinaldonitrile (7), and phenyllithium in ether-dioxan at — 10° gave 29, and benzaldehyde, 2-benzoyl-l,2-dihydroisoquinaldonitrile (8), and phenyllithium in ether-dioxan at —10° (or sodium hydride in refluxing... 

In principle, most of the syntheses of quinolizones could be applied to the synthesis of benzoquinolizones by starting with the quinoline or isoquinoline equivalent of the pyridine component. Thus Kappe84 has obtained the hydroxybenzo[ ]quinolizin-4-ones 70, and the hydroxybenzo[c]quino-lizin-l-ones 71 from methylquinolines, quinolyl- or isoquinolylacetates, and malonic esters or carbon suboxide. Kato and co-workers37-38 have used the Vilsmeier derivatives of 2-quinolylacetate with diketene (Eq. 39)37 or with anhydrides (Eq. 40)38 to give benzo[e]quinolizin-l-ones. 

Suggs and Jun exploited 8-quinolyl alkyl ketones 19-22 as substrates for C-C bond cleavage, as shown in Eq. 21. The formation of complexes 23-26 by insertion between the carbonyl carbon and the a-carbon is favored due to the general preference for five-membered chelate rings observed for cyclometalated complexes [42]. No deuterium is lost in the reaction of 8-quinolyl alkyl ketone 20, which has both benzylic positions deuterated. Interestingly, the chirality of the... 

Quinolyl cyclobutylmethyl ketone 72 undergoes C-C bond cleavage by rho-dium(I) to form the inserted intermediate 73, as mentioned in Eq. 21. Sequential (3-carbon elimination leads to ring-opening of the cyclobutane ring. Addition of pyridine and P(OMe)3 induces reductive elimination to give a mixture of linear 8-quinolyl ketones 74 and 75 [86]. 

Asymmetric dihydroxylation of the side-chain of Z-1-(4-meth-oxyphenyl)-1-(tert-butyldimethylsiloxy)-1-propene to give (R)-l-hydroxyethyl 4-methoxyphenyl ketone in 94% yield (99% e.e.) was effected by addition of the alkene to a stirred mixture of osmium tetroxide, potassium ferricyanide, potassium carbonate, a 9-0-(9 -phenanthryl)ether(PHN) of dihydroquinidine and 1 mole of methanesulphonamide in aqueous tert-butanol (1 1), with reaction during 16 hours at ambient temperature. Then treatment with sodium sulphite prior to work-up to gave the product (ref. 130). Other best ligands were the 9-0-(4 -methyl-2 -quinolyl) ethers (MEQ) of dihydroquinine. 

The Sg2 reaction on the 5p -like hybridized carbanion tends to proceed with inversion of the stereochemistry [45]. It is reasonable that a-thio carbanions, having higher s character than a-oxy carbanions, more frequently invert the stereochemistry on the anionic carbon in the reaction with electrophiles. As in the case of a-lithiated benzyl 2-pyridyl sulfide, the reaction of a-lithiated benzyl 2-quinolyl sulfide also proceeds through a dynamic thermodynamic resolution pathway. The quinolyl group is an excellent protecting group of thiols [46] and can be removed to yield the corresponding chiral thiols without racemization (Tables) [47]. 

A soln. of startg. oxime ester (prepared from biphenyl-4-carboxylic acid and benzophenone oxime) in carbon tetrachloride irradiated with a 400 W high-pressure Hg-lamp through a Pyrex filter under N2 at room temp, until reaction complete 4-chlorobiphenyl. Y 88%. This radical method is generally applicable to ar., hetar. (e.g. pyridyl, quinolyl, quinoxalyl), and aliphatic acids (prim., sec. and tert.). Ketone, amide, and hydroxyl groups remained unaffected. F.e.s. M. Hasebe, T. Tsuchiya, Tetrahedron Letters 29, 6287-90 (1988). 

Okada et al. investigated the binary system Pt-Co(MPQH) (where MPQH mono-8-quinolyl-o-phenylenediamine) [89]. The catalysts were heat treated in Ar atmosphere for 2 h. The optimum heat treatment temperature was 873 K. The mass specific catalytic activity of the binary catalysts supported on carbon was 5 A gn compared to 40-60 A gpt for PtRu. It was also shown that the nature and structure of the ligand coordinating the Co had an effect on performance. Co(NH3)6Cl3 did not exert any catalytic effect when combined with Pt, while porphyrin based complexes of Co heat treated at 1073 K yielded approximately 20 to 30 mV lower overpotentials compared to catalyst formulatiorrs using Co(MPQH). 

Chelation facilitates oxidative addition of unstrained C(carbonyl)-C bonds. For example, 8-quinolyl alkyl ketones underwent oxidative addition to rhodium(I) (Scheme 1.17) [25]. Addition of phosphorus ligands to the rhodacycle induced reductive elimination [26]. The stereochemistry of the a-carbon was retained during the oxidative addition/reductive elimination [27]. It was proposed that a tetrahedral intermediate arises by nucleophilic attack of rhodium on the carbonyl... 

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