Please explain in depth In the following a sequence propose a structure for A an

Question

Please explain in depth

In the following a sequence propose a structure for A and an explanation for the formation of propose from A. MCPBA OH DCM OH OH H20 OH O H-O OH Compound A is the above epoxide. Under basic aqueous the alcohol is deprotonated forming the nucleophilic alkoxide. It opens the epoxide attacking at the least substituted carbon (less steric hindrance) forming compound B as the major product. Under acidic conditions the epoxide is protonated making the epoxide more electrophilic. The neutral alcohol then opens the protonated epoxide attacking at the more substituted carbon (greater positive charge) forming compound C as the major product.

Explanation / Answer

The whole explanation for the formation of B and C is actually complete. However I will add something more in the formation of B. Because of the steric effects, one of the carbons of the epoxide is more substituted, you have a 2° and a 1° carbon. In basic conditions, we need to stabilize the charge, and in a nucleophilic attack, a nucleophile will attack on the side where it's less blocked. In this case, even though it can go through the 2° carbon, it will prefer to go to the 1° carbon to stabilize better. That's why in basic conditions you have B. In the case of C, in stronger acid conditions, the 2° carbon is actually more available; if you open the bond in the 2° carbon, you'll have a 2° degree carbocation, which is more stable than a 1° carbocation, that is why the neutral alcohol will do a nucleophilic attack on this carbon, to form C.

Hope this helps.

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---