Lithium trimethoxyaluminum hydride reduction

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-... 

Strict temperature control during carbonylation and reduction is crucial for success. Thus, carbonylation at -20 °C in the presence of 1.3 equiv of freshly prepared lithium trimethoxyaluminum hydride (LTMA) and reduction at -20 °C with 1 molar equiv of lithium aluminum hydride are carried out. 

Common catalyst compositions contain oxides or ionic forms of platinum, nickel, copper, cobalt, or palladium which are often present as mixtures of more than one metal. Metal hydrides, such as lithium aluminum hydride [16853-85-3] or sodium borohydride [16940-66-2]y can also be used to reduce aldehydes. Depending on additional functionalities that may be present in the aldehyde molecule, specialized reducing reagents such as trimethoxyaluminum hydride or alkylboranes (less reactive and more selective) maybe used. Other less industrially significant reduction procedures such as the Clemmensen reduction or the modified Wolff-Kishner reduction exist as well. 

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