Crystal structure and spectroscopic study of 6a,7a,13b,13c-tetrahydro-6a-hydroxy-2,3,11,12-tetramethoxy-6,6,8,8-tetramethyl-6H,8H-bischromeno-[3,4-b:4′,3′-d]furan,a dimer of precocene II 3,4-epoxide

The X-ray crystal structure of the title compound has been determined. The crystals are orthorhombic:Pcab, a=9.857(5),b=15.274(5),c=32.601(14) Å,V_c=4908.4 ų;Z=8;D_x=1.279 Mg m^–3; (MoK)=0.71069 Å;=0.88 cm^–1,F(000)=2016, temperature of measurement 294 K. The structure was solved by direct methods, and refined with 932 reflections to a finalR value of 0.071. The two six-membered rings show distorted boat conformations and the tetrahydrofuran ring exhibits a half-chair conformation. Mass spectra, IR spectrum, and¹H and¹³C NMR spectra are also reported.