Diisobutylaluminium

Enantiomerically pure /J-keto sulfoxides are prepared easily via condensation of a-lithiosulfinyl carbanions with esters. Reduction of the carbonyl group in such /J-keto sulfoxides leads to diastereomeric /J-hydroxysulfoxides. The major recent advance in this area has been the discovery that non-chelating hydride donors (e.g., diisobutylaluminium hydride, DIBAL) tend to form one /J-hydroxysulfoxide while chelating hydride donors [e.g., lithium aluminium hydride (LAH), or DIBAL in the presence of divalent zinc ions] tend to produce the diastereomeric /J-hydroxysulfoxide. The level of diastereoselectivity is often very high. For example, enantiomerically pure /J-ketosulfoxide 32 is reduced by LAH in diethyl ether to give mainly the (RR)-diastereomer whereas DIBAL produces exclusively the (.S R)-diastereomer (equation 30)53-69. A second example is shown in... 

E. Wini erfeedt, Applications of Diisobutylaluminium Hydride in Organic Syntheses, Synthesis 1975, 617. 

C15H13I2NO4 5563-89-3) see Dextrothyroxine diisobutylaluminium hydride (CgHijAl 1191-15-7) see Misoprostol diisohomoeugenol... 

The silane, prepared by reduction of tris(2-propylthio)silylenium perchlorate with diisobutylaluminium hydride at —78°C, is subsequently isolated by high-vacuum distillation from the mixture. Heating must be very mild to prevent explosion. 

Enantiospecific syntheses of amino derivatives of benzo[ ]quinolizidine and indolo[2,3- ]quinolizidine compounds have also been achieved via A-acyliminium ion cyclization reactions, as an alternative to the more traditional Bischler-Napieralski chemistry (see Section 12.01.9.2.2). One interesting example involves the use of L-pyroglutamic acid as a chiral starting material to construct intermediates 240 via reaction with arylethylamine derivatives. Diisobutylaluminium hydride (DIBAL-H) reduction of the amide function in 240 and subsequent cyclization and further reduction afforded piperidine derivatives 241, which stereoselectively cyclized to benzo[ ]quinolizidine 242 upon treatment with boron trifluoride (Scheme 47) <1999JOC9729>. 

Treatment of the amide 210 with diisobutylaluminium hydride (DIBAL-H) produces not only the expected reduction product 211 but also gives a mixture of the pyrrolonaphthyridine 212 and the indoloquinoline 213. Treatment of 212 with 50% acetic acid results in rearrangement to 213 (Equation 54) <1996JOC7882>. 

Esters 154 (R = C02Me) undergo reduction by treatment with diisobutylaluminium hydride (DIBAL-H) to form alcohols 154 in 17% yield (R = CH2OH) <2006BML1207>. 

In order to establish the correct absolute stereochemistry in cyclopentanoid 123 (Scheme 10.11), a chirality transfer strategy was employed with aldehyde 117, obtained from (S)-(-)-limonene (Scheme 10.11). A modified procedure for the conversion of (S)-(-)-limonene to cyclopentene 117 (58 % from limonene) was used [58], and aldehyde 117 was reduced with diisobutylaluminium hydride (DIBAL) (quant.) and alkylated to provide tributylstannane ether 118. This compound underwent a Still-Wittig rearrangement upon treatment with n-butyl lithium (n-BuLi) to yield 119 (75 %, two steps) [59]. The extent to which the chirality transfer was successful was deemed quantitative on the basis of conversion of alcohol 119 to its (+)-(9-methyI mande I ic acid ester and subsequent analysis of optical purity. The ozonolysis (70 %) of 119, protection of the free alcohol as the silyl ether (85 %), and reduction of the ketone with DIBAL (quant.) gave alcohol 120. Elimination of the alcohol in 120 with phosphorus oxychloride-pyridine... 

Diisobutylaluminium hydride catalyses the ring-closure of various dienes. It is proposed that the process involves addition of the aluminium hydride to a terminal double bond, followed by ring-closure and, finally, elimination of the catalyst (equation 106). Thus 1,5-hexadiene gives methylenecyclopentane (213) (equation 107), 1,6-heptadiene gives methylenecyclohexane (214) (equation 108), 4-vinylcyclohexene gives bicyclo[3.2.1]oct-2-ene (215) (equation 109) and the spiro compound 217 is obtained from 5-methylene-l,8-nonadiene (216) (equation 110)112. 

Tandem cyclization of l-cyclopropylidene-5-methylenecyclooctane (233) with palladium ) chloride/triphenylphosphine in the presence of diisobutylaluminium hydride leads to the [3.3.3]propellane 235 in 74% yield by way of the proposed intermediate 234 (L = ligand) (equation 119)120. 

In a similar procedure, through diisobutylaluminium hydride (DIBALH)-reduction of nitrile into imine and condensation with A-benzylhydroxylamine, C-(l-fluorovinyl) nitrones were synthesized (Scheme 2.30, Table 2.4) (228). 

In the presence of organometallic reagents (R1 MgX, R11u, diisobutylaluminium hydride (DIBAL-H)), the Weinreb amides 186 lead selectively to the corresponding carbonyl derivatives 187 as a mixture of Z/E isomers which spontaneously undergo partial cyclization to dihydropyrrolizines 188 (Scheme 42). This cyclization was completed by refluxing the cmde mixture in chloroform in the presence of silica gel <2002S2450>. 

It is interesting to note that this methodology allows the preparation of 4-functionalized indole derivatives starting from a simple acyclic precursor in a one-pot sequence. To prepare N-unsubstituted indoles, we choose the allyl moiety as a result to its stability to strong basic conditions and the variety of methods for its removal.[20] We therefore used an approach based on the isomerization/hydrolysis of the allyl groups with diisobutylaluminium hydride (DIBAL-H) and a... 

An efficient primary amine synthesis via iV-diisobutylaluminium imines has been described. A cyanide R CN (R1 = Bu, CsHn, Ph, 2-furyl or 2-thienyl) is treated with diisobutylaluminium hydride and the product is converted into the amine by reaction with an organomagnesium or organolithium compound R2M (R2 = Bu, t-Bu, allyl or benzyl)... 

Diethylaluminium hydride, 1719 Diethylethoxyaluminium, 2554 Diisobutylaluminium hydride, 3082 Dimethylaluminium hydride, 0936 Dipropylaluminium hydride, 2552 4-Ethoxybutyldiethylaluminium, 3372 Ethoxydiisobutylaluminium, 3373... 

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... 

Aluminium, 0048 Ammonium phosphinate, 4554 Barium phosphinate, 0210 f Benzaldehyde, 2731 1,4-Benzenediol, 2333 Bis(hydrazine)tin(II) chloride, 4070 Calcium acetylide, 0585 Calcium phosphinate, 3931 Chromium(II) chloride, 4052 Chromium(II) oxide, 4241 Chromium(II) sulfate, 4244 Copper(I) bromide, 0265 Diacetatotetraaquocobalt, 1780 Diisobutylaluminium hydride, 3082 f 1,2-Dimethylhydrazine, 0955... 

Recently, diisobutylaluminium hydride (DIBAH) was found to be a selective reducing agent in the reduction of steroidal 5,7 and 22,24(28) dienes (equation 32)100. 

R = BOM, = MOM. (TMS = trimethylsilyl, KHMDS = potassium hexamethyidisilazide, MOM = methoxymethyl, DIBAL-H = diisobutylaluminium hydride, Tr = triphenylmethyl, DMAP = 4-N,N-dimethylaminopyridine, TBAE = tetrabutylammonium fluoride, BOM = benzyloxym ethyl)... 

Alternatively, nitriles are selectively reduced by diisobutylaluminium hydride, (DIBAL-H) to imines followed by hydrolysis to aldehydes ... 

Diisobutylaluminium benzeneteUurolate, generated in situ from diphenyl ditelluride and diisobutylaluminium (DIBAL), reacts with acetals, alkyl sulphonates and oxiranes, giving the expected tellurides in high yields. ... 

Diisobutylaluminium phenyl tellurolate, a highly air- and moisture-sensitive reagent, prepared by reaction of diisobutylaluminium hydride with diphenyl ditelluride, undergoes an in situ addition to a,jS-unsaturated carbonyl compounds, leading to the corresponding jS-phenyltelluroaluminium enolate. This intermediate is hydrolysed by aqueous HCl into jS-phenyltelluro compounds or smoothly affords an aldol reaction with aldehydes to give a-hydroxyalkyl-jS-phenyltellurocarbonyl compounds. 

Purine nucleosides of type 1.4 (1177) were prepared by the reductive cleavage at the anomeric position of the ribofuranosyl moiety of 1176 with diisobutylaluminium hydride (DIBALH). The reductive ring opening was explained by the initial formation of a Lewis complex (93TL4835). 

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