Diisobutylaluminum hydride. See

Amides can also be deacylated by partial reduction. If the reduction proceeds only to the carbinolamine stage, hydrolysis can liberate the deprotected amine. Trichloroac-etamides are readily cleaved by sodium borohydride in alcohols by this mechanism.237 Benzamides, and probably other simple amides, can be removed by careful partial reduction with diisobutylaluminum hydride (see Section 5.3.1.1).238... 

Diazoquinone-novolac resist, 506 Diazotization reaction, 941 DIBAH, see Diisobutylaluminum hydride... 

A structurally unusual 3-blocker that uses a second molecule of itself as the substituent on nitrogen is included here in spite of the ubiquity of this class of compounds. Exhaustive hydrogenation of the chromone (13-1) leads to a reduction of both the double bond and the carbonyl group, as in the case of (11-2). The car-boxyhc acid is then reduced to an aldehyde (13-2) by means of diisobutylaluminum hydride. Reaction of that intermediate with the ylide from trimethylsulfonium iodide gives the oxirane (13-3) via the addition-displacement process discussed earlier (see Chapters 3 and 8). Treatment of an excess of that epoxide with benzylamine leads to the addition of two equivalents of that compound with each basic nitrogen (13-4). The product is then debenzylated by catalytic reduction over palladium to afford nebivolol (13-5) [16]. The presence of four chiral centers in the product predicts the existence of 16 chiral pairs. 

Dichloro-2,2-difluoroethylene, 105 (Diethylamino)sulfur trifluoride, 110 Reduction reactions (see also Deoxygenation, Reductive. . . ) of acetals and ketals Dibromoalane, 237 Diisobutylaluminum hydride, 237 Triethylsilane-Tin(IV) chloride, 237 of acetates and other esters to alkanes Nickel boride, 197 Triphenylsilane, 334 of acyl halides to alcohols Sodium cyanoborohydride-Tin(II) chloride, 280... 

The Homer-Emmons addition of dialkyl carboalkoxymethylenephosphonates to aldehydes [22] has been widely used to generate a,p-unsaturated esters which, in turn, can be reduced to allylic alcohols. Under the original conditions of the Homer-Emmons reaction, the stereochemistry of the oc,(3-unsaturated ester is predominantly trans and therefore the trans allylic alcohol is obtained upon reduction. Still and Gennari have introduced an important modification of the Homer-Emmons reaction, which shifts the stereochemistry of the a,[i-unsaturated ester to predominantly cis [23], Diisobutylaluminum hydride (DIBAL) has frequently been used for reduction of the alkoxycarbonyl to the primary alcohol functionality. The aldehyde needed for reaction with the Homer-Emmons reagent may be derived via Swern oxidation [24] of a primary alcohol. The net result is that one frequently sees the reaction sequence shown in Eq. 6A. 1 used for the net preparation of 3E and 3Z allylic alcohols. 

Conversion to the Aldehyde. This transformation is accomplished through a two-step procedure. One such variant requires reduction to the alcohol (e.g. LiAllTt, H2O) and subsequent oxidation (e.g. Swem conditions). Alternatively, Wein-reb transamination " followed by Diisobutylaluminum Hydride or conversion to the thioester (see below) and subsequent Triethylsilane reduction, afford the desired aldehyde in excellent yields. Weinreb transamination proceeds with minimal endocyclic cleavage when there is a p-hydroxy moiety free for internal direction of the aluminum species. 

Hydroalumination. The treatment of alkynes with diisobutylaluminum hydride in hydrocarbon solvents results in a aT-addition of the Al-H bond to the triple bond to produce stereodefined alkenylalanes. The hydroalumination of alkynes is more limited in scope than the corresponding hydroboration reaction of alkynes (see Chapter 5) with regard to accommodation of functional groups and regioselectivity. Whereas hydroalumination of 1-alkynes is highly regioselective, placing the aluminum at the terminal position of the triple bond, unsymmetrically substituted alkynes produce mixtures of isomeric alkenylalanes. 

Preparation Gensler and Bruno prepared the reagent by refluxing 160 ml. of n 25% solution of triisobutylaluminum (Hercules Inc., Ethyl Corporation) in heptane for 2-3 hrs. Distillation afforded 27 ml. of colorless diisobutylaluminum hydride, b.p, 80-90°/0.05 mm. For another procedure see Eisch and Kaska. ... 

Whitesell s synthesis of ( )-sarracenin [( )-495] (Vol. 4, p. 501, Ref. 314) has been published in full." It is worthwhile noting certain difficulties reported at the end of the synthesis involving the apparently simple steps shown in Scheme 48. Partial reduction of the lactone function in 496 with diisobutylaluminum hydride requires two equivalents, the first of which is taken up by complexation with the carbomethoxy group. Even with this problem solved, the yield of sarracenin [( )-495] from 496 was only 15%, and it is impossible to see where the loss was because of the instability of the intermediate compounds.Because both epimers of 497 were available in an earlier step toward 496, Whitesell also synthesized the as yet unnatural episarracenin with an epimeric 8-methyl group. 

Schinzer and Langkopf (83) reported in 1994 their synthesis of various seven- and eight-membered iV-heterocyclic systems resembling the benza-zepine framework of cephalotaxine (Scheme 49) by means of tandem Beckmann rearrangement-allylsilane cyclization. Treatment of compounds 286 and 287 with diisobutylaluminum hydride yielded the heterocycles 288 and 289, respectively. [See Note Added in Proof, p. 264.]... 

Reducing agents Aluminum hydride. Bis-3-methyl-2-butylborane. n-Butyllithium-Pyridine. Calcium borohydride. Chloroiridic acid. Chromous acetate. Chromous chloride. Chromous sulfate. Copper chromite. Diborane. Diborane-Boron trifluoride. Diborane-Sodium borohydride. Diethyl phosphonate. Diimide. Diisobutylaluminum hydride. Dimethyl sulfide. Hexamethylphosphorous triamide. Iridium tetrachloride. Lead. Lithium alkyla-mines. Lithium aluminum hydride. Lithium aluminum hydride-Aluminum chloride. Lithium-Ammonia. Lithium diisobutylmethylaluminum hydride. Lithium-Diphenyl. Lithium ethylenediamine. Lithium-Hexamethylphosphoric triamide. Lithium hydride. Lithium triethoxyaluminum hydride. Lithium tri-/-butoxyaluminum hydride. Nickel-aluminum alloy. Pyridine-n-Butyllithium. Sodium amalgam. Sodium-Ammonia. Sodium borohydride. Sodium borohydride-BFs, see DDQ. Sodium dihydrobis-(2-methoxyethoxy) aluminate. Sodium hydrosulflte. Sodium telluride. Stannous chloride. Tin-HBr. Tri-n-butyltin hydride. Trimethyl phosphite, see Dinitrogen tetroxide. 

While most reducing agents lead to the expected bornylamines as products of the reduction of camphor oxime (see above), diisobutylaluminum hydride is a notable exception, as a ring-enlarged amine, (1/ ,47 )-1.8,8-trimethyl-2-azabicyclo[3.2.1]octane (67) is obtained in high yield when starting with the oxime of (+ )-camphor16, It has been used as the lithium salt in enantioselective deprotonation and elimination reactions (Section C.). 

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