Dimethylaluminum chloride

In the low-temperature reaction of 1 with dimethylaluminum chloride insertion into the Al-Cl bond was expected. Instead, insertion into a Al-C bond took place, as concluded from the reaction products. After the insertion process, a reductive elimination step led to the formation of the known aluminum compound 3937 and of an undefined polymer of the composition (Me5C5SiMe)ra.30 This surprising result has initiated further... 

In 1978, Tebbe and co-workers reported the formation of the metallacyde 4, commonly referred to as the Tebbe reagent, by the reaction of two equivalents of trimethylaluminum with titanocene dichloride. The expulsion of dimethylaluminum chloride by the action of a Lewis base affords the titanocene-methylidene 5 (Scheme 14.4) [8]. 

Some of the reactions (e.g., that of dimethylaluminum chloride in Table 2) involve redistribution of alkyl and halide groups between the metals. The boronic acids, ArB(OH>2, prepared by Sn/B transmetallation, have been used in Suzuki coupling reactions. It is remarkable that the bistributyltin derivative of 1,1 -binaphthyl undergoes... 

We note that while tin reagents have often been employed for the organoboron halides/ the use of organostannanes as starting materials can also be applied to the synthesis of heavier group 13 derivatives. In the context of polyfunc-tional Lewis acid chemistry, this type of reaction has been employed for the preparation of ort/ o-phenylene aluminum derivatives. Thus, the reaction of 1,2-bis(trimethylstannyl)benzene 7 with dimethylaluminum chloride, methylaluminum dichloride or aluminum trichloride affords l,2-bis(dimethylaluminum)phenylene 37, l,2-bis(chloro(methyl)aluminum)phenylene 38 and 1,2-bis(dichloroalumi-num)phenylene 39, respectively (Scheme 16). Unfortunately, these compounds could not be crystallized and their identities have been inferred from NMR data only. In the case of 39, the aluminum derivative could not be separated from trimethyltin chloride with which it reportedly forms a polymeric ion pair consisting of trimethylstannyl cations and bis(trichloroaluminate) anions 40. 

Reaction of the chloro ester 1-Me with the enol silyl ether 23 a in the presence of dimethylaluminum chloride afforded the [2-1-2] cycloadduct 20 (67% yield) (Scheme 6). Deprotection of the alcohol moiety with uBu4NF in THF gave an 83% yield of a mixture of the 5-keto ester 21a and the spiropentane derivative 22 (ratio 1 90). Upon running the reaction in a mixture of THF/water (ratio 1 1) instead of anhydrous THF, the 5-keto ester 21a was isolated exclusively [331. 

In the absence of a donor solvent the coordinative saturation of the aluminum atoms can only be achieved by dimerization. Thus, the reaction of lithium trimethylsilyl-terf-butylhydrazide with dimethylaluminum chloride afforded the dimeric hydrazide 31 [Eq. (13)], which has a six-membered... 

All manipulations are conducted by using appropriate inert-atmosphere techniques. Toluene and THF are refluxed over sodium benzophenone and MeOH over Mg and then distilled prior to use. The ligands SalenH2 and Salen BuH2 were synthesized as described previously. Dimethylaluminum chloride is available from Aldrich Chemical Co. 

Ene reaction of aldehydes. Aliphatic and aromatic aldehydes are not reactive enophiles however, in the presence of dimethylaluminum chloride, which serves as u mild Lewis acid catalyst and proton scavenger, ene reactions occur in reasonable to high yield. Use of C2HSA1C1 results in complex mixtures of products. This ene reaction is a useful route to homoallylic alcohols.2... 

Recently, substantial progress in stereochemistry of the cycloaddition reaction has been reported [34], Cycloaddition between optically active oxadiene 13 and l-acetoxy-2-ethoxy-ethylene, promoted by dimethylaluminum chloride, leads to dihydropyran 14, with a very high endo-exo stereoselectivity (54 1) and in an almost quantitative yield (see Scheme 6). When trimethylsilyl triflate was used as the promoter in this reaction, the reverse endo-exo selectivity (1 5) has been noted. The dihydropyrans obtained served as substrates for the synthesis of (3-d- and 3-L-mannopyranosides [34]. 

B-Bromocatecholborane, 47 Bromodimethylborane, 47 B-Chlorocatecholborane, 47 Chlorotriisopropoxytitanium, 213, 226 Copper(II) bromide, 112 Dialkylboryl trifluoromethane-sulfonates, 340 Dichlorobis( 1 -phenylethoxy)-titanium(IV), 12 Dichlorobis(trifluoromethane-sulfonato)titanium(IV), 102 Dichlorodiisopropoxytitanium(I V), 12 Diethylaluminum chloride, 173 Diethylaluminum fluoride, 25 Dimethylaluminum chloride, 5 Ethylaluminum dichloride, 5, 44, 306 Ferric chloride, 133 Ferric chloride-Silica, 134 Isobutyl(2,4,6-tributylphenoxy)-aluminum trifluoromethanesulfonate, 113... 

Diels-Alder catalysts Alkylaluminum halides, 5, 173 Boron trifluoride etherate, 43 Diethylaluminum chloride, 173 Dimethylaluminum chloride, 5 Sodium dodecyl sulfate, 281 Titanium(IV) chloride-Diethylaluminum chloride, 309... 

Diisobutyl(iodomethyl)aluminum, 114 Dimethylaluminum chloride, 5 Ethylaluminum dichloride, 5, 44, 306 Ethylmagnesium bromide-Methyl-aluminum bis(2,4,6-tri-r-butyl-phenoxide), 203 Isobutyl(2,4,6-tributylphenoxy)-aluminum trifluoromethanesulfonate, 113... 

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