Included are pyridine, thiophene, pyrrole, and furan. Benzofuran is the heterocyclic compound consisting of fused benzene and furan rings. Furfuryl alcohol is an organic compound containing a furan substituted with a hydroxymethyl group. Alder reaction of furan and maleic anhydride. Frequent oxidized forms contain a C3 to C9 hemiketal/heterocyclic bridge or will form furan/pyran derivatives. Benzofuran reacts preferentially in the furan ring rather than in the benzene ring. The molecule consists of a furan ring, containing both aldehyde and alcohol functional groups. THF can also be synthesized by catalytic hydrogenation of furan. The chemical structure of furanocoumarins consists of a furan ring fused with a coumarin. The PCP was contaminated with dioxin and furan (PCDD/PCDFs), resulting in dioxin-contaminated sediment. They consist of coumarin annulated with furan. It has an aldehyde group attached to the 2-position of furan. They are sometimes considered oxidized derivatives of furan. Furan-2-ylmethanethiol is an organic compound containing a furan substituted with a sulfanylmethyl group. Davanone, davan ether, davana furan and linalool are the major constituents of davana oil.