When 2-methylcyclopentanone is treated with the bulky base triphenylmethyllithium under

Chapter 18, Problem 67

(choose chapter or problem)

When 2-methylcyclopentanone is treated with the bulky base triphenylmethyllithium under thetwo sets of conditions shown, the two possible enolates are generated in differing ratios. Why isthis so?O OLiCH3 (C6H5)3CLi CH3OLiCH3Conditions A: Ketone added to excess base 72% 28%Conditions B: Excess ketone added to base 6% 94%To tackle this problem, you have to invoke the principles of kinetic versus thermodynamiccontrol (review Sections 11-6, 14-6, and 18-2); that is, which enolate is formed faster and whichone is more stable? Divide your team so that one group considers conditions A and the otherconditions B. Use curved arrows to show the fl ow of electrons leading to each enolate. Thenassess whether your set of conditions is subject to enolate equilibration (thermodynamic control)or not (kinetic control). Reconvene to discuss these issues and draw a qualitative potential-energydiagram depicting the progress of deprotonation at the two a sites.*An electron-transfer process (compare alkyne reduction, Section 13-6) that is the equivalent of adding