Complex sentence: Then, a Lewis acid reacts with an alcohol, producing a mixture of α/β anomers of the 2-glycoside, while the double bond settles in-between the third and the fourth carbon.
Split into simpler sentences: Then, a Lewis acid reacts with an alcohol, producing a mixture of α/β anomers of the 2-glycoside. The double bond settles in-between the third and the fourth carbon.