Enones reaction with tris aluminum

Reaction of 6-methoxy-l-tetralone (30) with methylmagnesium iodide gave the dihydronaphthalene (31) in high yield (Scheme 4). However, the transformation of 31 to the tetralone 33, via perbenzoic acid epoxidation followed by acid workup, was capricious and resulted in low yields. A better route was developed, involving hydroboration (hydrogen peroxide oxidation) to the alcohol 32, followed by Pfitzner-Moffatt oxidation to the tetralone 33 in an overall yield of 61%. Other oxidation methods were tried but with varied and poor results. Alkylation of the tetralone 33 with 3-bromopropyne yielded 34, which underwent hydration [mercury (II) acetate in acetic acid-formic acid] to the diketone (35). The enone (36) obtained by base catalyzed cyclization was ster-eospecifically reduced with lithium aluminum hydride to the allylic alcohol... 

Allyl acetates are readily converted to allylsilanes in good yields, when they are reacted with 0.5 equiv of tris(trimethylsilyl)aluminum etherate and 4-6 mol % of Pd(PPh3)4 in THF at 0-25 °C (Scheme 34).For the reaction with unsynunetrical allyl acetates, the trimethylsilyl group tends to attack the more substituted carbon of the allyUc system under Pd-catalyzed conditions. With 10 mol % of Mo(CO)e (toluene reflux for 2.5 h), on the other hand, the trimethylsilyl group selectively attacks the less substituted carbon as exemplified by the exclusive formation of geranyl(trimethyl)silane in 65% yield. Under the Pd-catalyzed conditions, many functional groups of synthetic importance (e.g., vinyl bromide, acetals, esters, and enones) remain intact. 

For example, when acyclic enones are exposed to tris(trimethylsilyl)aluminum (7) at room temperature, only the 1,2-addition product is observed, whereas the addition proceeds via a 1,4-addition process when the reaction is conducted at -78 C (compare entries 8 and 9 in Table 5). In contrast, a, -unsatu-rated aldehyde substrates only undergo 1,2-additions with reagent (7). 

Additions to Conjugated Systems. The reaction of TMSCF3 with a, 8-unsaturated aldehydes or ketones under fluoride activation affords almost exclusively the 1,2-addition products. " Moreover, the 1,4-addition pathway may also participate in some cases, and occurs predominantly in 2-perfluoroalkyl chromones and related systems (eq 22). A 1,6-addition process in a suitably substituted substrate has also been described. A more general method for the 1,4-addition of CF3 groups to different enones consisted in the prior complexa-tion of the carbonyl with a bulky Lewis acid [aluminum tris(2,6-diphenylphenoxide)]. ... 

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