Reduction of propargylic alcohols

The procedure described in this experiment exemplifies a general method [225] for the reduction of propargylic alcohols to -allylic alcohols. The first step in the reaction is the formation of the aluminium alkoxide -C=C-C-OAlH3. Subsequently one of the three hydrogen atoms attached to aluminum is transferred to the triple bond with formation of a 5-membered cyclic aluminum compound. Hydrolysis affords the -allylic alcohol. In the present case an -enyne alcohol is formed. 

STEREOSPECIFIC REDUCTION OF PROPARGYL ALCOHOLS (E)-3-TRIMETHYLSILYL-2-PR0PEN-l-0L (2-Propen-l-ol, 3-(tr1i ethy1s11yl)-, (E)-)... 

STEREOSPECIFIC REDUCTION OF PROPARGYL ALCOHOLS (E)-3-TRIMETHYLSILYL-2-PROPEN-1-0L... 

Reduction of propargyl alcohols. 3-Trimethylsilyl-2-propyne-l-ol (1), prepared as shown from propargyl alcohol, is reduced stereospecifically by SMEAH to (E)-3-trimethylsilyl-2-propene-1-ol (2). Reductions of propargyl alcohols with LiAIH4 are less rraws-selective. 

Reduction of Propargylic Alcohols with LiAlH4 or with Red-Al... 

Semireduction of internal alkynes in the presence of a transition metal catalyst (e.g., Ni2B, Pd/C) provides disubstituted cw-alkenes. On the other hand, dissolving metal reduction of alkynes or reduction of propargylic alcohols with LiAlH4 or with Red-Al [sodium bis(2-methoxyethoxy)aluminum hydride] furnishes tran -disubstituted alkenes. ... 

Reduction of propargylic alcohols to allylic alcohols. Corey et a/.1 reported in 1967 that reduction of the propargylic alcohol (1) with 0.1 M lithium aluminum hydride-sodium methoxide (mole ratio 1 2) in THF at reflux (3 hr.) followed by iodination gives specifically the y-iodo alcohol (2). Reaction of (2) with dimethylcopperlithium affords Irons, frerns-farnesol. 

An aluminum hydride reduction of propargylic alcohol 153 to trans alkene 156 was found to proceed through retro-1,3-Brook rearrangement to vinyl silane diol 155, followed by 1,3-Brook rearrangement back again. While the final product 156 was isolated directly after longer reaction times, immediate workup following the aqueous ammonia quench revealed the formation of... 

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