Hydroxyhopanone (1) was converted via two alternative routes (1→9→11a→12→14→15→16 and 1→10→17→18→19→20) to A-neohop-21-ene (16) and A-neohop-3-ene (20), respectively. These unsaturated hydrocarbons (16 and 20) were found to be identical; this provided evidence to confirm the 21β-H configuration for 1.