Synthesis and crystal structure (2 S ,4 aS ,6 aS ,6 bR ,8 aR ,12 aS ,12 bR ,14 bR )- N -benzyl-10-hydroxy-heptamethyl-13-oxoicosahydropicene-2-formylthiourea, C 38 H 55 N 3 O 3 S | Synapse