With tertiary allylic substrates and under SN2 conditions (good nucleophile and aprotic solvent), a concerted reaction is produced by the nucleophile attacking the carbon of the double bond with loss of the leaving group.

sn2 cousin 01

The attack occurs on the double bond since it is a less hindered position than the chlorine carbon.

sn2 cousin 02

No thoughts on “SN2 prime in allylic systems”