Science of Synthesis

Marsden, S. P., Science of Synthesis, (2005) 26, 1063.

The Friedel–Crafts acylation of alkenes offers an attractively convergent synthesis of enones.[‌78‌] However, the reactions of acid halides with acyclic alkenes usually generates, predominantly, the deconjugated β,γ-unsaturated ketone, either through hydride shift or ene-like pathways. The reaction is most effective for the synthesis of α,β-unsaturated ketones when carried out in the intramolecular manifold, as in the conversion of ‌86‌ into ‌87‌ (‌Scheme 21‌).[‌79‌] Alternatively, the use of cyclic alkenes such as cycloheptene (‌88‌) in intermolecular reactions can also lead to good yields of conjugated enones such as ‌89‌.[‌80‌] The reactions require the use of strong Lewis acids such as aluminum trichloride,[‌80‌,‌81‌] tin(IV) chloride,[‌79‌] or ethylaluminum dichloride.[‌82‌] The initial products of these reactions are frequently the β-halo ketones, which undergo elimination either spontaneously or on treatment with external base. A milder, more recent variant uses hydrated zirconia as a catalyst.[‌83‌] Carboxylic acids couple directly with alkenes under the action of polyphosphoric acid,[‌84‌] or with trifluoroacetic anhydride followed by treatment with base.[‌85‌] In the former case, high yields are usually only obtained for reactions such as acetylation where the acid is inexpensive enough to be used in large excess.

‌Meeeee 88‌ Meeeeee–Meeeee Meeeeeeee ee Meeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

8,8,8,8-Meeeeeeeee-8M-eeeee-8-eee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

Me 8.8 M ee MeMM (888 eM) eee eeeee eeee ‌88‌ (88.8 e, 88 eeee) eee eee eeeeeeeee eeee eeeeeeeeee eeeee eeeeeee eeeeeeee ee eeee e eeeeeeeee eeeee, eeeee eee eeeee ee 888°M/88 eMe eee 8 e. Mee eeeee eeee eeeeeee eee eeeee eeee eeeeeee (888 eM) (MMMMMMM: eeeeeeeeee), eeeeeee eeee eeeeee eeeeeeee (88 eM, 8.88 eee) eee 8 e ee ee eeeee eeeee, eee eeee eeeeeeeeeeee ee eeeee. Mee eeeeeee eee eeeeeeeee ee 8,8-eeeeeeeeeeeeee (88 eM) eee eeeeee ee 8°M eeeee eeeee. Me eee eeeeeee eeee eee eeeeee eeeee MeMe8 (88.8 e, 8.888 eee). Meeee 88 eee ee 8°M, eee eeeeeeeee eeeeeee eee eeeeeee eeee Me8M (8 M), eeeeee eeee 8% MeMMM8 eeee (8 × 888 eM) eee eeeee (888 eM), eeeee (Me8MM8), eeeeeeee, eee eeeeeeeeeeee ee eeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8) ee eeee ‌88‌ ee e eeeeeeeee eeeeeeeeeee eeeee; eeeee: 8.88 e (88%).

Meeeeeeeeee-8-ee Meeeee Meeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeee eeeeeeeee ee eeeeeeeee eeeeeeeee, eee eeeee ee eeeeeeeeee, eeee eeeeeeeeee, eee eeeeeeeee.

MMMMMMM: Meeeeeee eeeeeeeeeee eeee ee e eeeeee eeeeeeee ee eee eeeeeee eee eeeeee eeeeeeeee eeee eeeee.

Me e eeeeeee ee eeeeeeeeeeee (‌88‌; 888 e, 8.88 eee), MeMe (888 e, 8.88 eee), eee MM8 (888 eM) eee eeeee MeMe8 (888 e, 8.88 eee) ee eeeee eeeeeeee eeee 8 e, eeeeeee eee eeeeeeeeeee eeeeeee −88 eee −88°M. Meeeeeee eee eeeeeeeee eee 8 e, eee eee eeeeeeeeeee eeeeeee ee eeee ee −88°M. Mee eeeeeee eee eeeeee eeee eee MMe eee eee, eee eee MM8 eeeee eeeeeeeee. Mee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee eeee Me8MMe eee 8 e. Mee eeeeeee eee eeeeee, eeeeee eeee eee eeee, eee eeeeeeeee eeee MMMe8. Meeeeeeeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee eeee eee eeeeeee; eeeee: 888 e (88%); ee 888°M/8 Meee.

References

Meeeeee Meeeeeeeeee

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