8-Acetoxy-4-twistanone (8) has been obtained in one-step from decalin dione 4 and a rigorous chemical proof has been obtained by chemical conversion of 8 into 4-twistanone (6). Twistane (1), 1-twistanol (15), 1-twistane carboxylic acid (17), and 1-twistylamine (20) have also been synthesized from compound 8 and chemical proofs are included.