# Does 1-phenyl-1-keto-but-2-ene show positive iodoform test?

It is told often that only compounds having a methyl ketone and corresponding alcohols show positive iodoform test.

I tried to sketch a mechanism to show that 1-phenyl-1-keto-but-2-ene also gives iodoform test. However I haven't found any source that confirms that 1-phenyl-1-keto-but-2-ene shows iodoform test. Please check if there is any mistake in the mechanism:

This mechanism is very similar to the classical iodoform reaction mechanism.

• C-C double bond group not have larger -Ieffect as compared to C=O group and abstraction of H+ from C H bond is not so easy by OH-. This fact can be used here. – Fish92003 Apr 16 '20 at 14:01
• However the carbanion at gama position is stabilized by resonance. – anonymous Apr 16 '20 at 14:13
• Why space between keto and but? – Zenix Apr 16 '20 at 17:35

Enones react with with iodine and catalytic base under aqueous conditions to give $$\alpha$$-iodoenones (Ref.1). Pyridines are most often used for this, the reference quoted also uses $$\ce{K2CO3/DMAP}$$. They further show that reaction works for a range of enones including those with the $$\ce{RCOCH=CH-CH3}$$ grouping and no mention is made of $$\gamma$$-iodination. A "background" reaction was run with $$\ce{K2CO3/I2}$$ in aq. THF and no iodination was observed.
1. Marie E. Krafft, John W. Cran, "A Convenient Protocol for the α-Iodination of α,β-Unsaturated Carbonyl Compounds with $$\ce{I2}$$ in an Aqueous Medium," Synlett 2005, (8), 1263-1266 (DOI: 10.1055/s-2005-868495).