Allyl reaction with aluminum

Partially fluorinated vinyl ethers of fluoroolefins are quite susceptible to the action of Lewis acids. Reaction usually proceeds with ionization of the allylic C-F bond and results in formation of C=0 group and elimination of alkyl halide. Indeed, 3-chloro-2-methoxyhexafluoro-2-butene 82 reacts with A1C13 with formation of trichlorovinyl ketone 83, and cyclic alkoxyfluoroalkenes demonstrate similar behavior in reaction with aluminum or tin(IV) halides [170] ... 

An in situ method reported by Torii and coworkers for preparing a reactive allyllead reagent is attractive from the standpoint of convenience since it avoids the need to isolate the organometallic reagent. The reagent, which is formed by treatment of allyl bromide with aluminum foil (1.0 equiv.) and a catalytic amount of lead(II) bromide (0.03-0.1 equiv.) in ether, adds to a-aryl- and branched a-alkyl-aldim-ines in the presence of BF3-Et20 (entries 20-26, Table 2). Details of the structure of the reactive allyllead species and its mechanism of formation are not clear. The reaction does not extend to enolizable ke-timines. 

Propargylic alcohols are reduced by reaction with lithium aluminum hydride and subsequent hydrolysis to ( J-allylic alcohols via an organoaluminum intermediate (A) as shown below ... 

Allylmagnesium bromide, 41, 49 reaction with acrolein, 41, 49 5-Allyl-l,2,3,4,5-pentachlorocyclopen-tadiene, 43, 92 Allyltriphenyltin, 41, 31 reaction with phenyllithium, 41, 30 Aluminum chloride, as catalyst, for isomerization, 42, 9 for nuclear bromination and chlorination of aromatic aldehydes and ketones, 40, 9 as Friedel-Crafts catalyst, 41, 1 Amidation, of aniline with maleic anhydride, 41, 93... 

Later, Torii et al. found that the tin-aluminum-mediated allylation can be carried out with the less expensive allyl chloride, instead of allyl bromide, when a mixture of alcohol-water-acetic acid was used as the solvent.77 When combined with stoichiometric amounts of aluminum powder, both stoichiometric and catalytic amounts of tin are effective. As reported by Wu et al., higher temperatures can be used instead of aluminum powder.78 Under such a reaction condition, allyl quinones were obtained from 1,4-quinones, followed by oxidation with ferric chloride. Allylation reactions in water/organic solvent mixtures were also carried out electrochemically, with the advantage that the allyltin reagent could be recycled.79... 

Later, Araki et al. found that the allylation of aldehydes and ketones can be carried out by using catalytic amounts of indium(III) chloride in combination with aluminum or zinc metal.109 This reaction was typically performed in a THF-water (5 2) mixture at room temperature, although the conversion was much slower compared to the same reaction mediated by use of a stoichiometric amount of indium and it required days to complete. When the reaction was carried out in anhydrous THF alone, the yield dropped considerably and side-reactions such as reduction to alcohol increased. The combinations of Al-InCL or Zn-InCl3 gave comparable results. 

The second pathway is represented by Eqs. (8)—(11). These reactions involve reduction of the Nin halide to a Ni° complex in a manner similar to the generation of Wilke s bare nickel (37, 38) which can form a C8 bis-77-alkyl nickel (17) in the presence of butadiene [Eq. (9)]. It is reasonable to assume that in the presence of excess alkyaluminum chloride, an exchange reaction [Eq. (10)] can take place between the Cl" on the aluminum and one of the chelating 7r-allyls to form a mono-77-allylic species 18. Complex 18 is functionally the same as 16 under the catalytic reaction condition and should be able to undergo additional reaction with a coordinated ethylene to begin a catalytic cycle similar to Scheme 4 of the Rh system. The result is the formation of a 1,4-diene derivative similar to 13 and the generation of a nickel hydride which then interacts with a butadiene to form the ever-important 7r-crotyl complex [Eq. (11)]. 

When the metallic additive to the intermediate 374 was zinc dihalide (or another Lewis acid, such as aluminum trichloride, iron trichloride or boron trifluoride), a conjugate addition to electrophilic olefins affords 381 . In the case of the lithium-zinc transmetallation, a palladium-catalyzed Negishi cross-coupling reaction with aryl bromides or iodides allowed the preparation of arylated componnds 384 ° in 26-77% yield. In addition, a Sn2 allylation of the mentioned zinc intermediates with reagents of type R CH=CHCH(R )X (X = chlorine, bromine) gave the corresponding compounds 385 in 52-68% yield. ... 

The ene reaction is strongly catalyzed by Lewis acids such as aluminum chloride and diethylaluminum chloride204 Coordination by the aluminum at the carbonyl group increases the electrophihcity of the conjugated system and allows reaction to occur below room temperature, as illustrated in Entry 6. Intramolecular ene reactions can be carried out under either thermal (Entry 3) or catalyzed (Entry 7) conditions 205 Formaldehyde in acidic solution can form allylic alcohols, as in entry 1. Other carbonyl ene reactions are carried out with Lewis acid catalysts. Aromatic aldehydes and acrolein undergo the ene reaction with activated alkenes such as enol ethers in the presence of Yb(fod)3 206 Sc(03SCF3)3 has also been used to catalyze ene reactions.207... 

As AL is one of the most potent 3,4,5-trisubstituted phenethylamines yet described, and since the corresponding amphetamines are of yet greater potency, it would be a good guess that 4-allyloxy-3,5-dimethoxyamphetamine (3C-AL) would be an interesting compound to explore. It could be made from syringaldehyde in reaction with allyl iodide, followed by the formation of a nitrostyrene with nitroethane, followed by reduction with aluminum hydride. It is, as of the present time, both unsynthesized and unexplored. 

Selective reduction of 530 with DIBAL gave a mixture (1 3) of the allylic alcohols 531 and 532 via preferential delivery of hydride to the unsaturated carbonyl function from the exo face. The allylic alcohol 531 was then converted to the allylic ether 533 by reaction with diazomethane in the presence of anhydrous aluminum chloride, whereas the major allylic alcohol 532 was converted to... 

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