Science of Synthesis

Nubbemeyer, U., Science of Synthesis, (2008) 32, 112.

But-3-yn-2-ones ‌229‌ add bromine monochloride or iodine monochloride and may form the corresponding α,β-dihalogenated enones ‌230‌ and/or their isomers ‌231A‌/‌B‌ in reactions run at room temperature. However, the results obtained depend upon the conditions employed; thus, when dichloromethane is the solvent the anti-Markovnikov products ‌231B‌ are the predominant products but in the presence of pyridine, as an acid scavenger, the stereochemical preference is changed and the E-congeners ‌231A‌ become the favored products. If methanol is used or heat is applied the nature of the products is again altered. Several representative examples are collected into ‌Scheme 79‌.[‌190‌]

‌Meeeee 88‌ Meeeeeee ee Meeeeee Meeeeeeeeeee ee Meeeee Meeeeeeeeeee ee Mee-8-ee-8-eeee[‌888‌]

‌Meeeeeeeeee 88‌

Meeeee eeeeeeeeeeee eeee eeee ee eeeeeee eeeee eeeeeee eee eee eeeeee eee eeeeeeeeeeeee eeeeeeeeeeeee eeeeeee ‌888‌ eee ‌888‌ eeee M eeeeeeeeeee. Meeeeee, ee 8,8-eeeeeeeeeeeeee ee eeeeeeeeeeeeeee eee eeeeeeeee eeee eeeeee eee eeeeeeeeeeee ‌888‌. Me eeee eeeee eeee eeeeee 8-eeeeeeeeee-8-eeeeee (‌888‌) eeeeeeeee eeeeeeeeeeeeeee ee eeee eee eeeeeeeeeeeee eeeeeeeeeeeeeee (‌Meeeee 88‌).[‌888‌]

‌Meeeee 88‌ Meeeeeeee ee Meeeee Meeeeeeeeeee ee Meeeeee[‌888‌]

‌Meeeeeeeeee 88‌

e e.e = eee eeeeeeee.

e Me 8,8-eeeeeeeeeeeeee eeee eeeeeeeee ee eeeee.

e Me MM8Me8.

Meeeee eeeeeeeeeeee eeee ee eeeeeeeee ee eeeeee (M)-8-eeeeee-8-eeeeeeeeee (‌888‌, M = Me) ee 88% eeeee, eeeeeee eeeeee eeeeeeeeeee eeeee (M)-8-eeeee-8-eeeeeeeeee (‌888‌, M = Me) ee 88–88% eeeee (‌Meeeee 88‌).[‌88‌,‌888‌,‌888‌] (M)-8-Meeee-8-eeeeeeeeee ee eeee ee e eeeeeeeee ee eeeeeeee eee ee eee eeeeeeeee ee eeeeeee eeeeeeeeeee.[‌888‌]

‌Meeeee 88‌ Meeeeeeee ee (M)-8-Meee-8-eeeeeeeeeee[‌88‌,‌888‌,‌888‌]

Meeee eeeeeeee ee eee eeeeeeee ee eeeeeee eeeeeeee ee eeeeeeeee ee eeeeeee eee eeeeeeee,[‌888‌–‌888‌] eee ee eeeeeeee eeee eeeeeeeeeee ee eeee eeeee.[‌888‌]

Meeeeeeeeeee Meeeeeeee

(M)-8-Meeeee-8-eeeeeeeeee (‌888‌, M = Me):[‌888‌]

Meeeeeeee eee eeeeeee eeeeeeeeeeee eeee MMe (88 e, 88 eeee) ee 8 M MMe (88 eM) eeeeeeeeee ee −88°M eee 8 e. Meeee eeeeeeee eee eeeeeee ee eeee ee ee, ee eee eeeeeeeee eeee eeeeeee (8 ×) eee eee eeeeeeee eeeeeeee eeee eeeeee eeee eee. ee Me8M8M8, eeeee (MeMM8), eee eeeeeeee. Mee eeeeeeee eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeeee e eeeeee eeeeee; eeeee: 8.8 e (88%); Me 8.8 (eeeeee eee, eeeeeee).

(M)-8-Meeee-8-eeeeeeeeee (‌888‌, M = Me):[‌88‌,‌888‌]

Meeeeeeee eee eeeeeee eeeeeeeeeeee eeeeeee e eeee ee MMe (8 e, 88.88 eeee) ee 88% MMe (88 eM) eeee ee 8°M eee 8 e. Mee eeeeeeeeeee ee eee eeeeeee eee eeee eeeeee ee ee eee eeeeeeee eee eeeeeeeee eee 8 e. Mee eeeeeee eee eeeeeeeee eeee eeeeeee (8 ×) eee eeeeee ee ee ee eee eeeeeeeee eeeeeeeeeeee eeeeeeeee. Mee eeeee eeeeeeee eee eeeeeeee ee e eeeeeeeee eeeeee; eeeee: 8.8 e (88%). Meee eeee eeeeeeeee eee eeeeee ee (888 eee ee MMe) eee eee eeeeeee eeeeeee eee eeeeee eeeee eeeeeeeee eee 88 e eee eeeee eee eeeeeeeee ee 88%.[‌888‌]

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8, 888.
• 8.Meeeee-Meee, (8888) M 88e8, 888.