(a) The product expected from nucleophilic addition of an ylide to an aldehyde or ketone b...

(a) The product expected from nucleophilic addition of an ylide to an aldehyde or ketone belongs to a class of substances called betaines. Like ylides, betaines contain a positively charged and a negatively charged atom and both have an octet of electrons; they differ from ylides in that the two charged atoms are nonadjacent. Write a structural formula for the betaine corresponding to nucleophilic addition of methylenetriphenylphosphorane to cyclohexanone.

(b) Use curved arrows to show the conversion of the betaine in (a) to an oxaphosphetane.

(c) Use curved arrows to show the one-step conversion of the betaine in (a) to methylenecyclohexane and triphenylphosphine oxide.

Sample Solution (a) Nucleophilic addition of the ylide to the carbonyl group leads to C—C bond formation.