Diethylaluminium chloride

The stereoselectivity of the thermal ring-closure of the dodecatrieneones 42 is determined by the nature of the remote group R. trans-Fused products 43 predominate over cw-products 44 and their ratio increases as R varies from MeO through Me to H (equation 29). If the reactions are catalysed by diethylaluminium chloride only fraws-compounds are formed. The homologues 45 behave similarly34. In contrast, the 7-azadeca-l,3,9-trienes 46 (X, Y = H2 or O) yield more of the cis- than the traws-fused compounds, regardless of the nature of X and Y (equation 30)35. 

The biaryl compound (50) forms a complex with diethylaluminium chloride to provide a catalyst able to promote enantioselective reaction between cyclo-pentadiene and methacrolein or acrylates (Scheme 45). The addition of A -tert butyl 2,2-dimethylmalonate to the reaction mixture was found to enhance the enantiomeric excess of the product11311. 

Diethylaluminium bromide, 1670 Diethylaluminium chloride, 1671 Diisobutylaluminium chloride, 3064 Dimethylaluminium bromide, 0882 Dimethylaluminium chloride, 0883 Ethylaluminium bromide iodide, 0841 Ethylaluminium dibromide, 0842 Ethylaluminium dichloride, 0843 Ethylaluminium diiodide, 0844 Hexaethyltrialmninimn trithiocyanate, 3695 Methylaluminium diiodide, 0423 Triethyldialuminium trichloride, 2556 Trimethyldialuminium trichloride, 2556 See Other ALKYLMETAL HALIDES... 

The first step in the total synthesis of the alkaloid ( )-ipalbidine 104 was the reaction of the diene 103 with A1-pyrrol ine (equation 60)53. The proportions of threo- and m // TO-dihydro- -pyridones, 106 and 107, respectively, produced in the diethylaluminium chloride-catalyzed reactions of the a-benzyloxyimines 105 (R = n-CsHn, i-Pr or i-Bu) with the diene 86 (equation 61), depend on the nature of R and the amount of imine used54. 

Note that the catalyst of Figure 10.6 contains the same titanium part as that of Figure 10.5, but that they differ in the aluminium Lewis acid and anions formed. The use of diethylaluminium chloride (DEAC, the common initiator for heterogeneous titanium catalysts) gave propene dimerisation only. This... 

When the chiral a,jS-enone enoate 98 was treated with magnesiocuprates in the presence of 1.5-2 equivalents of diethylaluminium chloride, the anti addition product 99 was obtained in moderate yield and with good diastereoselectivity (Scheme 6.21) [43, 44]. A reasonable explanation might assume a chelating coordination of the aluminium reagent [45]. Thus, if the enone 98 were to adopt an s-trans conformation, as indicated for complex 100, subsequent front side attack of the nucleophile would furnish the major diastereomer anti-99. 

Lithium-metal exchange in the lithium-)—)-sparteine complexes 399 or 402, respectively, by diethylaluminium chloride or triisopropoxytitanium chloride proceeds with inversion providing useful reagents for enantioselective homoaldol reactions... 

A pretty good diastereocontrol was achieved in the six-membered ring cyclization of 47, where diethylaluminium chloride and a catalytic amount of CuBr2 SMe2 were used to promote the internal attack of the Reformatsky centre to the sterically hindered carbonyl unit to give 48a and 48b (equation 32)108. 

Electron-withdrawing fluorine atoms are introduced on the methylenic a-carbon by the Reformatsky reaction of Boc-leucinal with ethyl bromodifluoroacetate in the presence of activated zinc dust with no diastereoselection. Under thermodynamic control, the y -isomer is obtained almost exclusively (Scheme 16)J15 The use of additives such as diethylaluminium chloride-silver(II) acetate enhances the chemical yield of the reaction, but also presents the disadvantage of being nonstereoselectiveJ78 ... 

The compound is capable of exothermic pressure generating decompositions, from about 170°C [1]. A short account of an explosion in a tank( ) used for polymerisation. It is thought that excess catalyst (diethylaluminium chloride) caused the polymerisation to run out of control. It should have been at 55°C but reached 234°C and 5.4 MPa[2]. 

Diethoxy-1,3 -disiladioxetane, 1758b f 1,2-Diethoxy ethane, 2541 f Diethoxymethane, 2010 f 3,3-Diethoxypropene, 2854 f Diethyl acetal, see 1,1-Diethoxyethane, 2540 Diethyl acetylenedicarboxylate, 2982 Diethylaluminium bromide, 1664 Diethylaluminium chloride, 1665 Diethylaluminium hydride, 1713 Diethylaluminium 2,2,2-trifluoroethoxide, 2460 f Diethylamine, 1720... 

Diethylaluminium bromide, 1664 Diethylaluminium chloride, 1665 Diisobutylaluminium chloride, 3059 Dimethylaluminium bromide, 0878 Dimethylaluminium chloride, 0879 Ethylaluminium bromide iodide, 0837 Ethylaluminium dibromide, 0838 Ethylaluminium dichloride, 0839 Ethylaluminium diiodide, 0840 Hexaethyltrialuminium trithiocyanate, 3688 Methylaluminium diiodide, 0422 Triethyldialuminium trichloride, 2551 Trimethyldialuminium trichloride, 1288 See ALKYLALUMINIUM DERIVATIVES (references 1,2)... 

Methanesulfonyl chloride Diethylaluminium chloride Orpholinopropanesulfonic acid buffer Benzyl-a-bromopropionate trans-l-(p-Nitrobenzyloxycarbonyl)-4-hydroxy-L-proline Methanesulfonyl chloride t-Butyldimethylsilyl chloride... 

Table 2 Reaction of azetidine-2-thioacetals 71 with diethylaluminium chloride (Equation 18)...

The reduction of azetidin-2-one 302 containing a thioacetal moiety at C-4 to the corresponding acetal azetidine, followed by diethylaluminium chloride promoted C(2)-N(l) bond cleavage, afforded bicyclic pyrrolidines 303 and pyrroles 304 (Equation 98) <1999JOC9596, 1998TL467>. 

Note that only ca 1% of the titanium atoms introduced with TiCl3 into the system give rise to the formation of surface active sites (since most of the titanium atoms remain inside the solid TiCl3 particles) [40], However, such active sites exhibit rather low stereospecificity in propylene polymerisation. The activity and stereospecificity of catalysts based on the / -TiCl3 modification also depend on the type of alkyl aluminium compound used as the activator. The application of triethylaluminium leads to a catalyst of much higher activity but of much lower stereospecificity, and on account of this diethylaluminium chloride is used for the polymerisation of propylene and other a-olefins, while triethylaluminium (and also triisobutylaluminium) is used for ethylene polymerisation [28],... 

Other well-defined catalysts for epoxide polymerisations, containing an isolated metal atom, have been derived from the reaction of diethylaluminium chloride with a Schiffs base [37-40]. For instance, 2,2 -[(l / ,2/ )-1,2-cyclo-hexylenebis(nitrilomethylidene)]diphenolato aluminium chloride [(sal)AlCl] appeared to produce low molecular weight poly(propylene oxide) characterised by a narrow distribution of molecular weights [40] ... 

Polyesters were yielded [scheme (41)] by polymerisations run with diethylzinc as the catalyst [281,286,287], but polyketones were obtained [scheme (42)] when dimethylketene was polymerised with triethylaluminium or diethylaluminium chloride [288] (Table 9.3) ... 

The mechanism of Lewis acid-catalysed ene reactions was studied for reaction of 2-methyl-butene 44 with formaldehyde in the presence of diethylaluminium chloride in toluene 92... 

At the same time the conversion of 11/54 — 11/59 (Scheme II/9) was published, an alternative way was found, which is summarized in Scheme II/9. The lithium derivative of (phenylthio)methyl phenyl sulfone adds nearly quantitative into ketones, in the presence of diethylaluminium chloride. The rearrangement (e.g. 11/61—> 11/62) proceeds smoothly on treatment of the tertiary alcohol, 11/61, with an approximately sixfold excess of diethylaluminium chloride [46]. An alternate reagent, the lithium salt of methoxy methyl phenyl sulfone, in a similar reaction yielded, enlarged a-methoxy cycloalkanones. The latter reaction sequence is restricted to the expansion of four- and five-membered rings [46]. 

Azetidines having a 4-methoxyphenyl, styryl, or 2-furyl group at C(2) and a benzyl or allyl substituent on nitrogen, when exposed to diethylaluminium chloride, give alkenes, stereoselectively through a fragmentation process (Scheme 29) <1999JOC9596>. 

The Trost-Mikhail ketones ring expansion procedure described before (see Section III.E) for the addition of a-lithio-a-methoxy sulfone 340 to cyclic ketones to give a-methoxycycloalkanones (Scheme 93) can be carried out with compound 419 to yield a-(phenylsulfanyl)cycloalkanones525. Smooth addition of intermediate 419 to ketones took place in the presence of diethylaluminium chloride and subsequent warm-up afforded the corresponding a-phenylsulfanyl ketones 420 (Scheme 110)525. 

An interesting synthesis of block copolymers by cationic polymerization of vinyl compounds was described by Kennedy and Melby [277] who used 2-chloro-6-bromo-2,6-dimethylheptane as coinitiator. Br- is eliminated by triethylaluminium, and styrene can be polymerized, without transfer, on the generated carbocation. After all the styrene has reacted, diethylaluminium chloride is added to eliminate Cl- from the coinitiator and thus produce new carbocations on the polymer chain. In the presence of 2-methylpropene, the two-block copolymer poly(styrene)-6/ock-poly(2-methylpropene) is formed. 

A synthetic method for preparing polyisoprene having a cis-, A linkage of 99.0% or greater using diethylaluminium chloride with the rare earth salt neodymium tris(bis (2-ethylhexyl)phosphate) is described. Reproducible Mooney viscosities of 85 and higher were also observed. 

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