The ketone shown is converted to its silyl enol ether under thermodynamic (equilibrating) conditions: Et3N, Me3SiCl, DMF, heat. Which structure is the major silyl enol ether?

MolSynapse / Question bank / Aldehydes, Ketones and Carboxylic Acids / Alpha hydrogens, enolisable positions and haloform test on drawn compounds

JEE Advanced levelSingle correct optionDifficulty 3 of 3co246

The ketone shown is converted to its silyl enol ether under thermodynamic (equilibrating) conditions: $Et X_{3} N$ , $Me X_{3} SiCl$ , DMF, heat. Which structure is the major silyl enol ether?

AStructure A
BStructure B
CStructure C
DStructure D

Answer: C

The drawn compound is 2-methylcyclopentanone. Equilibrating weak-base conditions give the more substituted (tetrasubstituted C=C) enol ether; kinetic LDA conditions would give the less substituted one (Structure A). Structure B is C-silylation and D has the oxygen on the wrong carbon relative to the ring methyl.

Practice Aldehydes, Ketones and Carboxylic Acids More on Alpha hydrogens, enolisable positions and haloform test on drawn compounds

Previous questionNext question

The ketone shown is converted to its silyl enol ether under thermodynamic (equilibrating) conditions: EtX3​N, MeX3​SiCl, DMF, heat. Which structure is the major silyl enol ether?

Answer: C

More questions on Alpha hydrogens, enolisable positions and haloform test on drawn compounds

The ketone shown is converted to its silyl enol ether under thermodynamic (equilibrating) conditions: $Et X_{3} N$ , $Me X_{3} SiCl$ , DMF, heat. Which structure is the major silyl enol ether?