Science of Synthesis

Trauner, D., Science of Synthesis, (2008) 32, 549.

The deprotonation of ketones can often be achieved with a high level of control. Regioselectivity issues arise when unsymmetrical ketones have α-protons available on both sides of the carbonyl group. These can be overcome by deprotonating under kinetic or thermodynamic conditions. Kinetic enolates are formed by deprotonation at the least-hindered and kinetically most-acidic site, which usually leads to less substituted and thermodynamically less stable enolates. In the case of enones and vinylogous esters, the position next to the carbonyl group undergoes faster deprotonation under kinetic conditions (α- vs γ′-deprotonation). The regioselective formation of kinetic enolates has been studied and reviewed in great detail, and some examples are given in ‌Scheme 3‌.[‌6‌–‌9‌]

8-Meeeeeeeeeeeeeeeeee (‌8‌) eee ee eeeeeeeeeeee eeeeeeeeeee ee eee eeeeeeeeeeeeeeeee eeee eeeeee eee eeee eeeeeeeeeee eeeeeeee.[‌8‌] Meeee eeeeee ‌8‌ eeeeeeeee eeeeeee eeeeeeeeeeeee eee eeeeeeeeeeeeee eeeeeeeeee ee eeeee eeeeeeeeeeeeeee ‌8‌.[‌8‌] [Meee eeee eeeeeeee eeeeeeee ‌8‌ eee ee eeeeeeeeeeee eeeee eeeeeeeeeeeee eeeeeeeeee ee eeeeee e eeeeeeeee eeeeeee (eee Meeeeee ‌88.8.8.8.8.8‌, ‌Meeeee 8‌).] Mee Meeee–Meeeeeeee eeeeeeeeee eeeee eeeeeeeee ee eee eeeeeeeee eeeeeee eeeeeee ee eee α-eeeeeeee ee eeeeeeeeee eeeeee (e.e., ‌88‌).[‌8‌] Meeee eeeeeeeee eeeeeeeeee eeeeeeeeee, eeeeeeeeeee eee ee eeeeeeee eeeeeee eeeeee eeeeeeeeeee eeeeeeeee. Mee eeeeeeee, eeeeeeee eeeeee ‌88‌ eeeeeeeee eeeeeeeee eeeeeeeeeeeee eee eeeeeeeeeeeeeeeeeeeeeeeeeeee ee eeeee e 88:8 eeeeeee ee eeeee eeeeeeeeeeeeeeeeeeeeeeeeee ‌88‌ eee ‌88‌.[‌8‌]

‌Meeeee 8‌ Meeeeee Meeeeeeeeeeee ee Meeeeee[‌8‌–‌8‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeeeeeee-8(8M)-eee (‌8‌); Meeeeee Meeeeeeee:[‌8‌]

M eeee ee MMM (88.8 eeee) ee eeeeeee (88 eM) eee eeeeeee eeee MMM (888 eM) eee eee eeeeeeeee eeeeeee eee eeeeee ee −88°M. Mee eeeee eeeeee ‌8‌ (8.88 e, 88.8 eeee) ee MMM (88 eM) eee eeeee eeeeeeee ee eeee eeee eeee e 88-eee eeeeee, eeee eeeeeeee eee eeeeeeeee eeeeeee. Mee eeeeeeeee eeee eee eeeeee ee eee eeeeeee eeeee eeee 88 eee, eeeeeeee eee 8 e, eee eeeeee ee ee. Mee eeee eee eeeeeeee eeee ee MM8Me eee eeeeeeeee eeee Me8M. Mee Me8M eeeeeeee eeee eeeeee eeee ee MeMMM8 eee eeeee, eeeee, eee eeeeeeeeeeee. Mee eeeee eeeeeeee eee eeeeeeeee ee eeeeeee eeeeeeee; eeeee: 8.88 e. Meeeeee eeeeeeeeeeee ee eeeeeeeeeeeeee eeeeeeee eeee eeeee-eeeeee; eeeee: 8.88 e (88%); eee eeee eee-eeeeee; eeeee: 888 ee (88%).

(8eM,8M,8M,8eM)-8-(eeee-Meeeeeeeeeeeeeeeeee)-8-(eeeeeeeeeeeeeee)-8,8e,8,8,8,8e-eeeeeeeeeeeeeeeee-8-ee Meeeeeeeeeeeeeeeeeeeeeeee (‌88‌) eee (8eM,8M,8M,8eM)-8-(eeee-Meeeeeeeeeeeeeeeeee)-8-(eeeeeeeeeeeeeee)-8,8e,8,8,8,8e-eeeeeeeeeeeeeeeee-8-ee Meeeeeeeeeeeeeeeeeeeeeeee (‌88‌):[‌8‌]

Mee eeeeee (‌88‌; 8.88 e, 8.88 eeee) eee eeeee eeeeeeee ee e eeeeeee eeee ee 8.8 M MMMMM ee eeeeeee (88.88 eM, 8.88 eeee) ee eeeee MMM (88 eM) ee −888°M eeee 8 e. Meeee ee eeeeeeeeee 8 e, e eeeeeee eeee ee MeMMe8 (8.88 e, 8.88 eeee) ee eeeee MMM (88 eM) eee eeeee eeeeeeee eeee 8 e. Mee eeee eee eeeeeee ee −888°M eee eeeeeee ee eeee ee ee eeeeeeeee. Mee. ee MeMMM8 (88 eM) eee eeeeeee (88 eM) eeee eeeee eee eee eeeeeee eee eeeeeee ee eeee eee 8 e. Mee eeee eee eeeeeeeee eeee MeMMe (8 × 88 eM). Mee eeeeeeee eeeeeee eeeeee eeee eeeeee eeee eeeee (8 × 88 eM), eeeee (MeMM8), eeeeeeee, eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeeee/MeMMe/Me8M 88:8:8) ee eeeeee ee eeeeeeeeeee eeeeeee ee eeeeeeee ‌88‌ eee ‌88‌ (88:8 ee 8M MMM) ee eeeee, eeeeeeeeeee eeeeeee; eeeee: 8.8 e (88%).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88e, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 888.