What is the mechanism for the following reaction?
Here's what I get.
The overall reaction
A ketone reacts with
The reaction mechanism
The carbonyl oxygen attacks the
The new complex undergoes an intramolecular rearrangement to form the gem-dichloride.
An alternative to Step 4
Instead of being concerted, Step 4 could consist of three steps:
- Step 4a. A
#"Cl"^"-"#ion leaves the #"P"#atom of the complex.
- Step 4b.
#"OPCl"_3#is an excellent leaving group. It departs in an #"S"_text(N)1#ionization to form a resonance-stabilized carbocation.
- Step 4c. The
#"Cl"^"-"#ion attacks the carbocation and forms the gem-dichloride.