Tetralone, disubstituted

When the 1-monoximes or dioximes of 4-acetyl-l-tetralones are hydrogenated in the presence of palladium, mixtures of diastereoisomeric 1-aminotetralones are formed. The m-aminoketone isomers readily form dehydrobenzoisoquinuclideines (3,4-disubstituted-1,4-dihydro-1,4-ethano-isoquinolines). Quaternary immonium salts prepared from these bicyclic imines are then converted by bases to bicyclic enamines [2,4-disubstituted-3-alkylidene-1,4-ethano-1,2,3,4-tetrahydroisoquinolines (25)]. 

When a prochiral nucleophile is reacted with 1,3-disubstituted allylic systems, the issue of diastereo- as well as enantioselectivity arises. In the alkylation of a tetralone, both the acyclic... 

A similar reaction was described by Nakamura et al. as recently as 2009. Here again, silver salts were not the best catalysts. Nevertheless, silver triflate was able to rearrange 2-alkynyl tetralones to 1,2-disubstituted naphthalenes (Scheme 3.55).83... 

The enol formed by irradiation of a-disubstituted indanones and tetralones bearing at least one hydrogen in the y-position undergoes enantioselective tautomerization to ketone in the presence of catalytic amounts of optically active aminoalcohols [74]. 

Major synthetic routes to the benzomorphans have dictated that a substituent appears in the 6-bridgehead position (5-position in earlier numbering). Synthetic difficulties were encountered where pyridine starting materials were not equipped with an appropriate 4-substituent (Scheme 4.9, p. 165) or where 2-tetralones were not disubstituted in the 1-position (Scheme 4.1, p. 156). During early studies the 6-substituent was usually a low alkyl function (Me, Et, or n-Pr). This work has been reviewed thoroughly by Eddy and May.(1)... 

The effect of the basic reagent has been studied in the methylation of phenylacetone. Monomethylation proceeds better with sodium isopropoxide than with sodium ethoxide. Introduction of a second alkyl group is accomplished best with potassium t-butoxide. Sodium t-amylate allows many alkylations that fail or give poor results when carried out with sodium amide. " 1,1-Disubstituted 2-tetralones are conveniently prepared by alkylation in the presence of sodium hydride, no monosubstituted products being formed with this reagent, ... 

A diastereoselective 6-exo-tng cyclization of (318), producing the trans-disubstituted tetralone (319) upon treatment with BF3-Me2S at low temperature, has been reported. This cyclization can be regarded as an intramolecular Michael-type addition with umpolung at the imine carbon. The mechanism includes an internal... 

Ishida, N. Sawano, S. Murakami, M. Synthesis of 3,3-Disubstituted [Small Alphaj-Tetralones by Rhodium-Catalysed Reaction of l-(2-haloaryl) Cyclobutanols. Chem. Commun. 2012,48,1973-1975. 

Ishida N, Sawano S, Murakami M (2012) Synthesis of 3,3-disubstituted a-tetralones by ihodium-catalysed reaction of l-(2-haloaryl)cyclobutanols. Chem Commun 48(14) 1973-1975. doi 10.1039/c2ccl6907j... 

Rhodium(I)-catalyzed reactions of l-(2-bromophenyl)cyclobutanol 47a afforded a 3,3-disubstituted 1-tetralone 48a (Scheme 3.27) [37]. The reaction was proposed to involve oxidative addition of the aryl-Br bond to the alkox-orhodium(I) species, followed by P-carbon elimination. Azetidin-3-ol 47b could be used instead of cyclobutanols to furnish isoquinolinone 48b. 

This general method has been applied in particular to the case where Rj = CH3 and R2 = CHjCgHj. Vast synthetic possibilities are thus available for the preparation in high yields of indanone and tetralone derivatives disubstituted in the 2 position. These arene complexes (e.g., LXVII) are also of considerable use in annulation reactions (Jaouen and Meyer, 1976) and in the synthesis of spiro compounds (Meyer et al, 1977). 

The highly electrophilic cationic bis(8-quinolinolato)aluminum complex 407 enabled Yamamoto and coworkers to perform Mukaiyama-Michael additions of silyl enol ethers to crotonylphosphonates 406. The procedure was not only applicable to enol silanes derived from aryl methyl and alkyl methyl ketones (a-unsubstituted silicon enolates) but also to several cycfic a-disubstituted silyl enol ethers, as illustrated for the derivatives of a-methyl tetralone and indanone 405 in Scheme 5.105. Despite the steric demand of that substitution pattern, the reaction occurred in relatively high chemical yield with varying diastereoselectivity and excellent enantiomeric excess of the major diastereomer. The phosphonate residue was replaced in the course of the workup procedure to give the methyl esters 408. The protocol was extended inter alia to the silyl enol ether of 2,6,6-tetramethylcyclohexanone. The relative and absolute configuration of the products 408 was not elucidated [200]. 

Rhodium catalysis allows the formation of 3,3-disubstituted a-tetralones from l-(2-haloaryl)cyclobutanols. The reaction is likely to involve a five-membered rho-dacycle (94), followed by opening of the four-membered carbocyclic ring to give a seven-membered rhodacycle (95). The tetralone product is formed following reductive... 

H nin and co-workers reported the results from the irradiation of a-disubstituted indanones, tetralones, and propiophenones bearing at least one hydrogen in the y-position in the presence of catalytic amounts of optically active aminoalcohols. The reaction provided the Norrish type 11 cleavage compounds with an enantiomeric excess reaching 89% (e.g., Scheme 19). Synthesis of 3-hydroxyindene by a Norrish type II elimination as well as the mechanistic aspects of this reaction were discussed by Jefferson and... 

Tetralones 26 mono- or disubstituted with methoxy or hydroxy group in the aromatic ring were reduced to 2-tetralols 27 in good yields ig. 8) and with high e.e. s by nonfermenting BY [56]. With BY the tricyclic ketone 28 was stereoselectively reduced to afford the alcohol 29 albeit with moderate yield [57]. 

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