Ketones react with dimethylsulfonium methylide to yield epoxides. Suggest a mechanism for the reaction.?
Assume, the substrate is cyclohexanone and choose the correct options :
Ketones react with dimethylsulfonium methylide to yield epoxides. Suggest a mechanism for the reaction.?
Assume, the substrate is cyclohexanone and choose the correct options :
The correct options are
A dimethylsulfonium methylide is a sulphur ylid
B The mechanism involves a nucleophilic addition
C The mechanism involves an intramolecular substitution
In the first step, the carbon nucleophile attacks the electrophilic carbonyl carbon in what looks similar to an addition reaction – like in the case of attack by CN− at the carbonyl carbon.
In the next step, the negatively charged, oxygen (one of the three lone pairs) nucleophile attacks the carbon from the ylid
and displaces dimethyl sulphide (which, like water, is a capable leaving group). This reaction differs from Wittig Olefination (how?).
Also, this is a nucleophilic addition followed by a substitution (conventional intramolecular).
But ths cannot be construed as an acyl substitution because the leaving group is part of
the attacking nucleophile and not attached to the carbonyl of the original substrate!
A
dimethylsulfonium methylide is a sulphur ylid
B
The mechanism involves a nucleophilic addition
C
The mechanism involves an intramolecular substitution
In the first step, the carbon nucleophile attacks the electrophilic carbonyl carbon in what looks similar to an addition reaction – like in the case of attack by CN− at the carbonyl carbon.
In the next step, the negatively charged, oxygen (one of the three lone pairs) nucleophile attacks the carbon from the ylid
and displaces dimethyl sulphide (which, like water, is a capable leaving group). This reaction differs from Wittig Olefination (how?).
Also, this is a nucleophilic addition followed by a substitution (conventional intramolecular).
But ths cannot be construed as an acyl substitution because the leaving group is part of
the attacking nucleophile and not attached to the carbonyl of the original substrate!
