Trimethoxyaluminum hydride, lithium

Triphenylstannane reduced the double bond in dehydro-)J-ionone in 84% yield [872], Complex copper hydrides prepared in situ from lithium aluminum hydride and cuprous iodide in tetrahydrofuran at 0° [873], or from lithium trimethoxyaluminum hydride or sodium bis(methoxy-ethoxy)aluminum hydride and cuprous bromide [874] in tetrahydrofuran at 0° reduced the a,p double bonds selectively in yields from 40 to 100%. Similar selectivity was found with a complex sodium bis(iron tetracarbonyl)hydride NaHFe2(CO)g [875]. 

Reduction of unsaturated ketones to unsaturated alcohols is best carried out Nit v complex hydrides. a,/3-Unsaturated ketones may suifer reduction even at the conjugated double bond [764, 879]. Usually only the carbonyl group is reduced, especially if the inverse technique is applied. Such reductions are accomplished in high yields with lithium aluminum hydride [879, 880, 881, 882], with lithium trimethoxyaluminum hydride [764], with alane [879], with diisobutylalane [883], with lithium butylborohydride [884], with sodium boro-hydride [75/], with sodium cyanoborohydride [780, 885] with 9-borabicyclo [3.3.1]nonane (9-BBN) [764] and with isopropyl alcohol and aluminum isopro-... 

Esters are also reduced by sodium aluminum hydride (yields 95-97%) [<9<9] and by lithium trimethoxyaluminum hydride (2 mol per mol of the ester) [94] but not by lithium tris tert-butoxy)aluminum hydride [96], Another complex hydride, sodium bis(2-methoxyethoxy)aluminum hydride, reduces esters in benzene or toluene solutions (1.1 -1.2 mol per ester group) at 80° in 15-90 minutes in 66-98% yields [969], Magnesium aluminum hydride (in the form of its tetrakistetrahydrofuranate) reduced methyl benzoate to benzyl alcohol in 58% yield on refluxing for 2 hours in tetrahydrofuran [59]. 

Lithium triethoxyaluminum hydride, 68 Lithium trimethoxyaluminum hydride, 62... 

Lithium trimethoxyaluminum hydride [1,625, before references]. The reagent greatly enhances the reaction of carbon monoxide with organoboranes.4 The reaction can... 

Carbonylation of organoboranes Carbon monoxide. N,N -Carbonyl-diimidazole. 2,3-Dimethyl-2-butylborane. Hydrogen fluoride—Antimony pentafluoride. Lithium trimethoxyaluminum hydride. Palladium (II) chloride. 

Synthesis of aldehydes by carbonylation. Brown s original synthesis of aldehydes by reaction of trialkylboranes with carbon monoxide in the presence of lithium trimethoxyaluminum hydride (see Carbon monoxide, 2, 60) sufFered from the disadvantage that only one of the three alkyl groups was utilized thus the maxi-... 

This reducing agent is mentioned by Brown and Shoaf, but the main interest in this paper is centered on lithium trimethoxyaluminum hydride. 

For a series of substituted cyclohexanones and norbornanones, it was found that lithium trimethoxyaluminum hydride had a higher tendency than lithium tri-/-butoxyaluminum hydride to add to the less hindered side of the molecule. Suggest possible explanations for this behavior. 

There is a reagent named lithium triethylhorohydride and another named lithium trimethoxyaluminum hydride. Draw both reagents. Speculate on the strength of the first reagent relative to sodium horohydride and the second relative to lithium aluminum hydride. 

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