Aldehydes & Ketones - Synthesis I
For each of the conversions shown on the left, provide the reactants and reagents necessary to convert the starting material into the final product. Pay particular attention to the regiochemistry and stereochemistry of the reactions you utilize.Click the mouse on the final product to view the answer;
click on the arrow for help with the synthesis.
In order to prepare 1-(N,N-diethylamino)-1,3-cyclohexadiene from 2-cyclohexenone, the carbonyl must be converted to an intermediate immonium ion, which will loose a hydrogen from the g-position on the ring to form the conjugated enamine. The reactions conditions are simply treatment with diethylamine.
The target molecule is simply the dimethylketal of 2-cyclohexenone. Ketals can be prepared from the corresponding ketone by reaction with the corresponding alcohol in the presence of an acid catalyst.
In order to prepare 1-phenylethanol from benzaldehyde, a methyl group must be added to the carbonyl carbon, with the conversion of the carbonyl into an alcohol. Alkyl groups can be readily added to a carbonyl carbon using the Grignard reaction.
In order to prepare toluene from benzaldehyde, the carbonyl group must be reduced to the hydrocarbon, without reducing the ring. This is readily accomplished using the Wolff-Kishner reduction (H2NN H2 in the presence of KOH), the Clemmensen reduction (Zn(Hg)/H3O+), the catalytic reduction of a dithioketal (with Raney Ni), or by mild catalytic hydrogenation of the aryl carbonyl (H2/Pt, 25o, 1 atm).
In order to prepare 1-(N,N-diethylamino)-1,3-cyclohexadiene from 2-cyclohexenone, the carbonyl must be converted to an intermediate immonium ion, which will loose a hydrogen from the g-position on the ring to form the conjugated enamine.
The target molecule is simply the dimethylketal of 2-cyclohexenone. Ketals can be prepared from the corresponding ketone by reaction with the corresponding alcohol in the presence of an acid catalyst.
In order to prepare 1-phenylethanol from benzaldehyde, a methyl group must be added to the carbonyl carbon, with the conversion of the carbonyl into an alcohol. Alkyl groups can be readily added to a carbonyl carbon using the Grignard reaction.
In order to prepare toluene from benzaldehyde, the carbonyl group must be reduced to the hydrocarbon, without reducing the ring. This is readily accomplished using the Wolff-Kishner reduction (H2NN H2 in the presence of KOH), the Clemmensen reduction (Zn(Hg)/H3O+), the catalytic reduction of a dithioketal (with Raney Ni), or by mild catalytic hydrogenation of the aryl carbonyl (H2/Pt, 25o, 1 atm).