Question

Mechanism. In the presence of various enamides, benzyne has been observed to undergo a series of cycloadditions and pericyclic ring opening to yield nitrogen heterocycles with high stereoselectivity. Propose a mechanism for the following reaction. (The formation of benzyne requires only as much detail as presented in the lab manual.) DME 85 °C O Iz Ⓡ 110 °C, 18h Helpful Hint 1: Benzyne is capable of performing [2+2] cycloaddition with electron-rich alkenes, as shown below: Оме MeOOME LOMe 0. mpen — Of Helpful Hint 2: Cyclobutene readily undergoes pericyclic ring opening to yield 1,3-butadiene.

Answer 1

ZO Fo DME , 85°C Ms 110c (2 +2] N 110°c m Electrocyclic a МА Ring Opening 110°c (4+2] Diels Alder Reaction