29 30 possibilities for 1, 4elimination of benzenesulfinic acid from 29, one would give a 1, 3- cyclohexadiene, the other a methylenecyclohexene. It turned out that the exocyclic elimination was highly favored from 29, using the same reaction conditions as above, and 30 was the only product formed (> 96% exocyclic diene). I2 This selectivity reflects the higher kinetic acidity of the allylic CHB compared to the other allylic proton.