Science of Synthesis

Braun, M., Science of Synthesis, (2007) 35, 341.

It is evident that only such protocols that provide a regioselective substitution in the case of unsymmetrical dialkyl ethers are useful. In addition, the method has been applied to the preparation of α,ω-dibromides ‌26‌ starting from either symmetrical diethers or from cyclic ethers (‌Scheme 26‌). Unsymmetrical ethers with alkyl residues of different degrees of substitution (methyl, primary, secondary, or tertiary) can be cleaved selectively depending on the conditions applied inasmuch as the less-substituted residues are cleaved by an SN2 mechanism, and the more-substituted ones by an SN1 mechanism. Applications of this concept, as well as the cleavage of cyclic ethers, have been reviewed comprehensively (see Houben–Weyl, Vol. 5/4, pp 418–428). In addition to hydrobromic acid, phosphorus tribromide and boron tribromide have also been reported as reagents for cleavage of ethers with formation of alkyl bromides.[‌104‌,‌105‌]

‌Meeeee 88‌ Meeeeeee ee Meeee Meee Meeeee, Meeeeee Meeeee, eee Meeeee Meeeee eeee Meeeeeee Meeeeee[‌888‌–‌888‌]

Meeeeeeeeeee Meeeeeeee

8,8-Meeeeeeeeeeee (‌88‌, e = 8):[‌888‌,‌888‌]

MMM (88 e, 88 eM, 8 eee) eee eeeee eeeeee ee e eeeeeee ee 88% ee MMe (888 e, 8 eee) eee eeeee M8MM8 (88 eM). Mee eeee eee eeeeeeee eee 8 e eee eeeeeeeeee eeeeeeeee ee eeeee eeeeeeeeeeee. Meee eee eeeeeeeeeeee eee eeeeeeee, eee eeeee eeeee ee eee eeeeeeeeee eee eeeeeeeee eee eeeeee eeee eee ee MeMMM8 eee M8M, eee eeeee (MeMe8, eeee M8M8). Meeeeeeeeeee eeeee eeeeeee eeeeeeee eeee eee eeeeeee ee e eeeeeeeee eeeeee; eeeee: 888–888 e (88–88%); ee 88°M/8 eMe ee 888–888°M/8 eee.

Meeee e eeeeeeee eeeeeeee eeeeeeee, 8,8-eeeeeeeeeeeeee eee eeeeeeee eeee eeeeeeeeeeeeeee ee 88–88% eeeee.[‌888‌]

References

Meeeeee Meeeeeeeeee

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