Allenes quinoline

Formation of Allenes. Quinoline can be used as an acid scrubber in the preparation of allenes via vinyl trifiate intermediates. The elimination of trifluoromethanesulfonic acid in quinoline proceeds in good yield (eqs 11 and 12). ... 

Attempts to liberate l-methyl-l-aza-2,3-cyclohexadiene (329) from 3-bromo-l-methyl-l,2,5,6-tetrahydropyridine (326) by KOtBu in the presence of [18]crown-6 and furan or styrene did not lead to products that could have been ascribed to the intermediacy of 329 (Scheme 6.70) [156], Even if there is no doubt as to the allene nature of 329 on the basis of the calculations on the isopyridine 179 and 3d2-lH-quinoline (257), it is conceivable that the zwitterion 329-Za is only a few kcal mol-1 less stable than 329. This relationship could foster the reactivity of 329 towards the tert-butoxide ion to an extent that cycloadditions to activated alkenes would be too slow to compete. On the other hand, the ultimate product of the trapping of 329 by KOtBu could have been an N,0-acetal or a vinylogous N,0-acetal, which might not have survived the workup (see, for example, the sensitivity of the N,0-acetal 262 [14], Scheme 6.57). 

Allenic sulfides 150 provide 2//-thiopyrans 104 and isomeric thiophenes 105 on heating with quinoline, probably through the path 150 - 102 - 103 - 104 + 105.148... 

The synthesis of a tetraphenyl derivative (rubrene, Expt 6.13) of the linearly fused tetracyclic aromatic hydrocarbon naphthacene involves an interesting intermolecular cyclisation process between two molecules of 1-chloro-1,3,3-triphenylpropa-1,2-diene. This substituted allene is formed in situ from 1,1,3-triphenylprop-2-yn-l-ol (Expt 5.41) when the latter is allowed to react with thionyl chloride and the resulting chlorosulphite ester heated with a little quinoline cyclisation occurs spontaneously under these reaction conditions to give rubrene which has an intense red colour. 

The proposed mechanism involves the initial rearrangement of alkynyl imine 137 into allenyl imine 138. Subsequent coordination of copper(I) to the terminal bond of the allene triggers intramolecular attack of the aromatic ring, a process that finally leads to quinolines 139 via several intermediates. 

The Wittig reaction can be used to generate quinolines after initial addition of allenes to anilines (Scheme 65) <1998T1647>. 

The eventual product of such reactions (after cleavage of the Zr-C bond during workup [51]) is an amine with a vinyl or alkyl substituent (arising from the alkyne or alkene) at the a position. Whitby thus derivatized tetrahydro-quinoline, following in situ generation of the zirconaaziridine 26, by alkyne, alkene, or allene insertion (Eq. 11) [52,53]. 

Nina A. Nedolya was born in Irkutsk (Russia) and educated in organic chemistry at the Irkutsk State University (Diploma 1972, PhD 1982, DSc 1998). From 1995 to 1999 she was associated with Prof. L. Brandsma at the Utrecht University (The Netherlands). In 1999 she obtained her second PhD from the Utrecht University. She is presently Head of the Research Group of Chemistry of Heterocyclic Compounds at A. E. Favorsky Irkutsk Institute of Chemistry. She is the author of over 210 review articles and research papers. She is also one of the inventors for 112 patents. She is interested in the chemistry of polyfunctional unsaturated heteroatomic systems (vinyl, allenyl, and alkynyl ethers and their derivatives, linear and cyclic heteropolyenes, hetero-cumulenes), including synthesis of important heterocycles, particularly pyrroles, thiophenes, thiazoles, imidazoles, dihydrofurans, dihydropyridines, pyridines, quinolines, dihydroazepines, and azepines, based on metallated allenes or alkynes and/or heterocumulenes. 

Photoadducts of 4-methoxyquinolin-2(lH)-one (142) with alkenes have again found use in synthesis. [,2 + 2] Addition to allene, for example, gave the l-methylene-l,2-dihydrocyclobuta[c]quinolin-3(4H)-one (143)," and an analogous addition of 4-methoxy-l-methylquinolin-2(lH)-one to 2-methyl-but-3-yn-2-ol has been used in a synthesis of ( )-edulinine." ... 

Allenic carbenes react with methylpyrroles and indoles to give 3-alkenyl pyridines 185 [87JCS(P1)1347] and quinolines 185 [R -l-R = (CH=CH)2] [76JCS(P1)2103] in low yield. 

Photoisomerization of ethyl 2-cyano-l,2-dihydroquinoline-l-carboxylate gave allene derivatives, but introduction of a methyl group at C4 of the quinoline changed the reaction course the product was then ethyl e t/o-l-cyano-6b-methyl-l,la,2,6b-tetrahydrocyclopropa[(>]indole-2-carboxylate (en /o-3a). ... 

The palladium-catalyzed cyclocarbonylation reaction of o-iodoanilines with allenes and CO in l-butyl-3-methylimidazolium hexafluorophosphate [bmimJPFg afforded 3-methylene-2,3-dihydro-lH-quinolin-4-ones in yields of up to 90% under a low pressure (5 atm) of CO (Scheme 17.2). The ionic liquid, as the solvent and promoter, enhanced the efficiency of the cyclocarbonylation reaction. In this work. Ye and group demonstrated the recyclability of the system of ionic liquids and their use as catalysts [44]. 

Allenes. AUenes can be prepared from ketones in a two-step procedure conversion to the vinyl triflate and elimination of triflic acid by quinoline at 100 . Unsymmetrical ketones give mixtures of triflates, but the same allene is... 

Anodic oxidation of N, N.-dimethylaniline in methanol yields the -methoxylated derivative (72), which reacts with substituted alkenes in the presence of Lewis acid to give a wide range of tetrahydroquinolines (e.g. 73).94- The adduct (75) from N-methylaniline and allene-1,3-dicarboxylic acid dimethyl ester (7 ) can be converted into the 4-quinolone (76) on treatment with polyphosphoric acid. 95 The use of nitrobenzenes as quinoline precursors is exemplified by the reaction sequence depicted in Scheme 17. The transition-metal-catalysed transformation is thought to involve the reduction of the nitrobenzene to the corresponding aniline via a nitrene intermediate.96... 

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