Furan, structure

Thieno[3,4-d][l,3]dithiol-2-one, 1-nitro-synthesis, 6, 1013 Thieno[3,4-c]furan, 4,6-dichloro-synthesis, 6, 1013 Thieno[3,4-c]furan, tetraphenyl-formation, 4, 1060 synthesis, 4, 1060 UV spectra, 4, 1044 Thieno[3,2-6]furans structure, 4, 1039 synthesis, 6, 1020 Thieno[3,4-c]furans... 

Reaction of vinylcarbenoids with furans offers another level of complexity because the furanocyclo-propanes in this case would be divinylcyclopropanes capable of a Cope rearrangement as well as electro-cyclic ring opening to trienes.27b c As illustrated in Scheme 42, the product distribution was dependent on the furan structure. With 2,5-disubstituted furans [3.2.1 ]-bicyclic systems (202) were exclusively formed, but with furan or 2-substituted furans, trienes (203) were also produced. 

Identified by Stoffelsma et at. (1968) in roasted coffee flavor. In fact, the authors did not specify the furanic structure but, as they referred to Stoll et al. (1967) for the m-isomer, there is little doubt about the identification. Friedel et al. (1971) confirmed the identification for the /ram-isomer in an aroma complex of coffee (method in Gianturco et al., 1963). Cantergiani et al. (2001) found it in a green Mexican arabica (1.56% of the volatiles by GC on a polar column). 

These changes as well as functional analytical data suggest that the yield of products in which cyclic fragments do not maintain the aromatic furan structure increases during oligomerization. The product yield of the conversion of a furan compound increases in the order FAlcatalyst effect and electronic... 

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