Reduction of acid chlorides and esters

Acid (acyl) chlorides can be converted to aldehydes using lithium tri-tert-butoxyaluminium hydride (LiAlH(Ot-Bu)₃). The hydride source (LiAlH(Ot-Bu)₃) is a weaker reducing agent than lithium aluminum hydride. Because acid chlorides are highly activated they still react with the hydride source; however, the formed aldehyde will react slowly, which allows for its isolation.

General reaction:

Example

Acid chlorides can be converted to aldehydes using lithium tri-tert-butoxyaluminium hydride (LiAlH(Ot-Bu)₃). The hydride source (LiAlH(Ot-Bu)₃) is a weaker reducing agent than lithium aluminum hydride. Because acid chlorides are highly activated they still react with the hydride source; however, the formed aldehyde will react slowly, which allows for its isolation.

General Reaction:

Example

Esters can be converted to aldehydes using diisobutylaluminium hydride (DIBAH).  The reaction is usually carried out at -78 ^oC to prevent reaction with the aldehyde product.

Example

Esters can be converted to 1^o alcohols using LiAlH₄, while sodium borohydride (NaBH4

) is not a strong enough reducing agent to perform this reaction.

Example

Mechanism

1) Nucleophilic attack by the hydride

2) Leaving group removal

3) Nucleophilic attack by the hydride anion

4) The alkoxide is protonated

Going from reactant to products simplified

Example