1.1- Dimethyl-2-tetralone

The procedure described is an example of a more general synthetic method for the direct conversion of ketones into cyanides. " The reaction has been carried out successfully with acyclic and cyclic aliphatic ketones, including numerous steroidal ketones and aryl-alkyl ketones. The conversion of diaryl or highly hindered ketones such as camphor and )3,j8-dimethyl-a-tetralone requires the use of a more polar solvent. The dimethoxyethane used in the present procedure should be replaced by dimethyl sulfoxide. ... 

The aromatization of the oxepin structure can be accompanied by other acid-catalyzed reactions such as the hydrolysis of ketals. Dimethyl 11 -oxo-6-oxabicyclo[5.4.0]undeca-l (7),2,4-triene-2,3-dicarboxylate ethylene ketal reacts in the presence of trifluoroacetic acid to give the tetralone system 3.133... 

Organomagnesium compounds react with imines, prepared from 3-methoxy-2-naphth-aldehydes by a 1.4-addition mechanism. This reaction can be performed with high diastere-oselectivity. The method was applied for the synthesis of optically pure S-tetralones . Vinyhnagnesium bromide reacts as an acceptor with a ketone dimethyl hydrazone zincate 207, yielding a 1,1-bimetallic species, which can be reacted sequentially with two different electrophiles (equations 131 and 132) . The reaction proceeds via a metalla-aza-Claisen rearrangement, where the dimethylhydrazone anion behaves as an aza-allylic system . 

Dihydroxy-l-tetralone Diisoprene 2,3-Dimethoxy-5,6-dimethyl-l,4-benzoquinone Isosclerone ( )-Limonene Aurantiogliocladin... 

Starting with this hypothesis, several 6-sila-steroids were prepared127-129. As an example, the syntheses of 6,6-dimethyl-6-sila-oestradiol (197) and 6,6-dimethyl-6-sila-mestranol (198) are described in Scheme 25. Not only the synthesis of the key intermediate 4,4-dimethyl-4-sila-6-methoxy-l-tetralone (7 96) but also the well known organic reactions, leading from 196 to 197 and 198, are strongly influenced by the specific properties of the silicon atom. Although known reactions of steroid chemistry could be used for further transformations from 196 to 197 and 198, conditions were not directly transferable because of the chemical behaviour of the Si-Calkyi and Si-Qryl bond. Important differences in the pH- and solvent profile were neces-... 

The excellent method for cyclizing o-benzylbenzoic acids to anthranol acetates, by heating the acid in- a mixture of acetic acid, and anhydride with zinc chloride as a catalyst,228 has been used also in the preparation of cyclic ketones of the tetralone type. In this way 7-3-acenaphthylbuty-ric acid has been cyclized in 78% yield 224 Y-2-phenanthrylbutyric acid48 and the 9,10-dihydro derivative97 in 51% and 59% yields respectively and a,j8-dimethyl-Y-2-naphthylbutyric acid in 90% yield.186... 

Encouraged by these successful results, Saigo and co-workers tested ligand 78 in the rhodium-catalyzed hydrosilylation of ketones.56 Indeed, asymmetric hydrosilylation of acetophenone and tetralone using 78 as a chiral source led to considerably improved enantioselectivities (94% and 89% ee, respectively) compared to reactions performed with valinol-derived phosphorous-containing oxazoline 66 (82% and 59%, respectively).59,60 The equal accessibility of the two enantiomers of the m-2-amino-3,3-dimethyl-l-indanol backbone in 78 represented an additional advantage over oxazoline 66, which is derived from an amino alcohol of the chiral pool because (5)-tetralol could easily be obtained using (-)-78 in 97% yield and 92% ee (Scheme 17.30).56... 

In addition, Koga and coworkers claimed a spectacular rate enhancement adding either 1,1,4,7,10,10-hexamethyltriethylenetetramine or ureas (such as Af,Af -dimethyl-N,N -propylene urea or iV -dimethyl-A iV -ethylene urea) as a substitute for HMPA during the alkylation of tetralone lithium salt in DME399. Interestingly, in the case of secondary alkyl halides, a kinetic resolution occurred in some particular cases with fair400 to excellent enantioselectivities401. 

Application of the dimethyl acetylenedicarboxylate reaction to enamines of cyclic ketones gave similar results the pyrrolidine enamines of cyclopentanone and a-tetralone gave the ring-expanded products (60 and 62, respectively) in toluene, and pyrrolizidines (61 and 63, respectively) in methanol (equation 32)53. 

An alternative cyclization via a 1-tetralone intermediate has been achieved by Inoue and May,(15) Scheme 4.5. The key intermediate (41) was prepared from frmercuric acetate gave a mixture of the three benzomorphans (42, 49% 43, 13% 44, 5%). Hydrogenation of 42 afforded 3,lla-dimethyl-8-methoxybenzomorphan (45). 

Recent work on the thermal indolization of arylhydrazones has introduced new synthetic possibilities for azaindoles. Kelly et al. refluxed cyclohexanone and deoxybenzoin 2-pyridylhydrazones in diethylene glycol to give 5,6,7,8-tetrahydro-a-carboline (42, R = H) and 2,3-diphenyl-7-azaindole in 70 and 56% yields, respectively, compared with 53 and 12% reported earlier. Similarly, y-carboline 29 was obtained in 95 % yield from cyclohexanone 4-pyTidylhydrazone (lit. 48% ). Several 7-azaindole derivatives were prepared in the same manner. The yields ranged from 5 % for azaindolenine (31) to 88% for 3-phenyl-7-azaindole. 3,3-Dimethyl-7-azaindolenine was obtained in 47 % yield from the isobutyralaldehyde hydrazone. The novel cyclic compounds 40 and 41 were obtained from the 2-pyridylhydrazones of cyclopentanone, a-indanone, and a-tetralone in 67, 95, and 77% yields, respectively. Unfortunately, all attempts to cyclize the acetone, pyruvic acid, and ethyl pyruvate hydrazones were unsuccessful. Also, cyclohexanone and methyl ethyl ketone 5-nitro-2-... 

The ferrocenylphosphine (R)-(S)-8a is also effective for the asymmetric allylation of several other active methine compounds, including 2-acetyl-1-tetralone, 6,6-dimethyl-2-acetylcyclohexanone, 2-acetylcyclooctanone, 1 -phenyl-2-methylbutane-1,3-dione, 2-phenylpropanal, and methyl a-isocyano(phenyl)acetate [43, 44], The allylation products and the values of enantiomeric excess are shown in Scheme 2-26. 

In Stork s synthesis (148), 5 - methyl - 6 - methoxy - 1 - tetralone (CLXXXIV) was converted into the tricyclic intermediate CLXX XVII in several steps involving condensation with dimethyl carbonate, addition of methyl isopropenylketone, and cyclization to the a, -unsaturated ketone CLXXXVI, followed by catalytic hydrogenation, replacement of the hydroxyl group in the resulting dihydro alcohol by a chlorine atom on treatment with phosphorus oxychloride in pyridine solution, and elimination of hydrogen chloride by methanolic sodium methoxide. 

The monomethylation of the pyrrolidine enamine of -tetralone shown in Scheme 41 provides a highly successful example of the reaction. Attempted alkylation of the ketone with 1 equiv. of methyl iodide in the presence of a strong base gave almost exclusively the recovered ketone and its dimethylated derivative. 

Trimethylcyclohex-2-enone(isophorone) readily condenses with salts (7) in the presence of sodium methoxide to orange-red heptatrienones (40)6 which begin at 90° to cyclize to 3,3-dimethyl-l-tetralones (41), losing dimethylamine ... 

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