Chapter 30.6, Problem 6P

Interpretation Introduction

Interpretation:

Reaction between 1,3-Cyclopentadiene and cycloheptatrienone is suprafacial or antarafacial to give the product which is given below:

Concept introduction:

[6 + 4] Cycloaddition is a type of cycloaddition between a six-atom pi system and a four-atom pi system, leading to a ten-membered ring. It is a thermally allowed, higher-order cycloaddition process. Although most linear, acyclic trienes do not give [6 + 4] products selectively, cyclic trienes give high yields of [6 + 4] products in many cases.

A suprafacial cycloaddition occurs when like phases of the p orbitals of both reactants are on the same side of the pie system, so that two bonding interactions result.

An antarafacial cycloaddition occurs when one pie system must twist to align like phases of the p orbitals of the terminal carbons of the reactants.