Synthesis and crystal structure of-(3 R ,5 S ,10 S ,13 S ,14 S )- N -(4-methoxy-2-methylphenyl)-10,13-dimethylhexadecahydrospiro [cyclopenta[ a ]phenanthrene-17,2′-[1,3]dioxolan]-3-amine, C ₂₉ H ₄₃ NO ₃