3-Tetralones

The pyrrolidine enamine of 2-tetralone (177) was converted to l-cyano-2-tetralone, which exists almost entirely in the enolic form (178), by reaction with cyanogen chloride (J23). Reaction of 177 with cyanogen bromide gave N-naphthylpyrrolidine (179), presumably via the unstable bromoenamine (180). The latter observation is in accord with the mode of reaction of the heterocyclic enamine (126) with cyanogen bromide, which resulted in the... 

In the same fashion, the phenylhydrazone of 2-tetralone 43 was found to provide only one isomer, carbazole 44, when heated in dilute sulfuric acid. ... 

More recent work in this series demonstrated that a carbonyl group can be interposed between the side-chaincarrying aromatic ring and the ethylene function with full retention of activity. Claisen condensation of benzoate with 2-tetralone affords the e-diketone Reaction of... 

The salicylic acid functionality incorporated in a rather complex molecule interestingly leads to a compound that exhibits much the same activity as the parent. The 1,4 diketone required for formation of the pyrrole ring can be obtained by alkylation of the enamine from 2-tetralone (38) with phenacyl bromide. Condensation of the product, 39, with salicylic acid derivative 40 leads to the requisite heterocyclic system (41). The acid is then esterified (42) and the compound dehydrogenated to the fully aromatic system (43). Saponification affords fendosal (44). ... 

Highly reactive mixed anhydrides can also promote acylation. Phenylacetic acid reacts with alkenes to give 2-tetralones in TFAA-H3P04.55 This reaction involves an intramolecular Friedel-Crafts alkylation subsequent to the acylation. 

Azines have been prepared by initial condensation of diethoxyphosphinyIhydrazine anions with aldehydes or ketones (Scheme 9). Phosphoryl azides undergo 1,3-dipolar cycloaddition to 2-tetralone enamines to give triazolines, possibly en route to amidines. A full paper on the addition of diethyl dibromophosphoramidate to alkenes(leading to the synthesis of 2-bromoalkylamines) has appeared. ... 

By analogy with die acid-induced ring contraction of cycloheptatrienyl ketones 233, high-yield rearrangement to 2-tetralones is possible 233 >. As Scheme 32 shows, substituents on the aromatic nucleus determine the regioselectivity of cyclopropa-... 

Rh2(OAc)4-catalyzed decomposition of m-methoxy-substituted diazoketones 244 furnishes 6-methoxy-2-tetralones rather than the expected bicyclo[5.3.0]decatrienones. This demonstrates that the direction of ring opening in the norcaradienone intermediate 245 may well be influenced by the nature and position of a substituent. 

Reaction of 1-tetralone with aryl cyanides or methyl thiocyanate, followed by aromatisation with DDQ gave good yields of benzoquinazolines. The further transformation of the methylthio product 31, via oxidation and selective sequential nucleophilic substitution of the resulting sulfones, illustrates the utility of this substituent. 2-Tetralone reacted similarly but substantial amounts of by-products were formed <06T2799>. 

Tetralone is readily mono- or di-alkylated at the 1-position to the exclusion of O-alky lation with a range of alkylating agents under liquiddiquid two-phase conditions without an added solvent [24], Similarly, it has been reported that anthrone undergoes mono- and di-C-alky lation at the 10-position with propargyl and allyl halides to the almost complete exclusion of O-alkylation [25]. It has been claimed that methyl-ation yields 9-methoxyanthracene [26],... 

The stereospecific C-alkylation of a range of benzylic ketones, such as tetralones, 2-phenylcyclohexanones and cycloheptanones, and 2-phenyl-y-lactones, has also been described [8]. For example, Af-(4-trifiuoromethylbenzyl)cinchonidinium bromide catalyses the reaction of 1,5-dibromopentane with 7-methoxy-l-methyl-2-tetralone to yield the (R)-l-(5-bromopentyl) derivative (75% yield with 60% ee). 

The Robinson annulation reaction of 7-methoxy-l-methyl-2-tetralone with methyl vinyl ketone in the presence of A,-(4-trifluoromethylbenzyl)cinchonidinium bromide produces the S-isomer of the tricyclic compound (Scheme 12.10) with an 81% conversion (81% ee) [8]. 

The preparation of 6-methoxy-2-naphthol is of particular interest as the starting point in many synthetic sequences. It is readily converted to 6-methoxy-2-tetralone through a Birch reduction... 

Transition state imbalance in the deprotonation of substituted 2-tetralones by hydroxide ions has been described. A Brpnsted plot of logA versus substrate pAfa is linear, with slope —a) of —0.60 0.01 but the negative deviation of the point for the 6-nitro derivative suggests that delocalization of charge lags behind proton transfer. ... 

From what was plarmed as a straightforward displacement of the chloride atom in 36 with hydrazine followed by a condensation with 2-tetralone and Fischer indolization to produce 39, dihydrazone 38 was isolated as an intermediate, resulting fi om dihydrazine 37 <99JHC441>. Subsequent Fischer indole cyclization and aminolysis of 38 produced 39 a mono-hydrazone intermediate (as opposed to 38) was ruled out by the authors on the basis of H NMR. 

Schmidt reaction on /3-tetralone yields a 2 1 mixture of the 2-benzazepin-3-one and 3-benzazepin-2-one, whereas the l-benzyl-2-tetralone (198 X = O) yields only l-benzyl-2-benzazepin-3-one (76HCA2059). 

For examples of Ru-catalyzed hydrogenation of N-(3.4-dihydro-2-naphthalenyl)-acetamide see (a) Renaud. J.L., Dupau, P., Hay. A.-E.. Guingouain. M., Dixneuf P.H. and Brtmeau. C. (2003) Ruthenium-catalysed enantioselective hydrogenation of trisubstituted enamides derived from 2-tetralone and 3-chromanone Influence of substitution on the amide ai m and the aromatic ring. Adv. Synth. Catal.. 345. 230-238. 

Synthesis (Freed and Potoski (American Home), 1971 Freed, 1973 Kleemann et al., 1999,) Dezocine is prepared through the following sequence The condensation of 1-methyl-7-methoxy-2-tetralone with 1,5-di-bromopentane by means of NaH or potassium tertbutylate affords 1 -(5-bromopentyl)-1 -methyl-7-methoxy-2-tetralone this product is cyclized with NaH to give 5-methyl-3-methoxy-5,6,7,8,9,10,11,12-octahydro-5,11 -methano-benzocyclodecen-13-one i. The ketone i, by reaction with hydroxylamine hydrochloride in pyridine, is converted into its oxime ii, which is reduced with H2 over Raney Ni to a mixture of isomeric amines which were separated by crystallization of the HCI salts giving 5-a-methyl-3-methoxy-5,6,7,8,9,11 a, 12-octahydro-5,11 -methanobenzo-cyclodecen-13p-amine, which is finally cleaved with concentrated HBr. 

Tetralin. The presence of an aromatic ring in the molecule induces important changes with respect to the saturated homologue (decalin). Firstly, the photochemical oxidation (i.e. in the absence of titania) is very important (see Fig. 1) as expected from the absorption spectrum it produces principally 2-tetralone as the main product and 1 -tetralone. Secondly, the photocatalytic oxidation occurs principally at position 1 (see. Fig. 1 and the following scheme). Note that this scheme refers to both photocatalytic and photochemical products however, because of the role of inner filter played by Ti02, the former products should be predominant. 

Fig. 1. Oxidation of tetralin by a) photocatalysis 1-tetralone (A) 2-tetralone (B) C02 (C) - b) photochemistry (i.e. without Ti02) 1-tetralone (A1) 2-tetralone (B1).

---