Cryatal and Molecular Structure of an Oxygenated Dimer of 3-Methylindole, (5aα, 10bα, 11aβ, 12β)-6-Acetyl-5a, 10b, 11a, 12-tetrahydro-10b, 12-dimethyl-6H-oxazolo[3,2-a : 4,5-b']diindol-12-ol