Furans, naturally occurring

Natural products find a place not as such but at points where, once again, their chemistry illustrates the behavior of their furan nuclei. There are now so many naturally occurring furans (the sea adds its quota to the land plant count every week) that even to make a list, as in the previous review, was too big a task and would have taken too much room happily, reference to almost any issue of Phytochemistry will immediately supply examples and there are already some good lists available elsewhere (eremophilane2 and farnesane23 furans, butenolides,3 furanoid fatty acids,4 marine products5). 

Furan-containing molecules are found in both natural products and pharmaceuticals. At one time, furfural was produced in great quantities from corncobs. Perillene, a secondary plant metabolite, is an example of naturally occurring furans. Furan is frequently used as a bioisostere of a benzene ring in medicinal chemistry. For example, Ranitidine (Zantac) marketed by Glaxo was one of the first blockbuster drugs with annual sales over 1 billion dollars. 

The intramolecular Diels-Alder methodology has been used in approaches to naturally occuring furan derivatives (93JCS(Pl)2395). For example, thermolysis of (311) gave the product (312) in almost quantitative yield by cyclization followed by isomerization of the exocyclic double bond to rearomatize the furan residue. The reaction proved to be highly stereoselective. 

Naturally Occurring Furan Derivatives The mass spectra of naturally occurring oxygen heterocyclics were reviewed only recently.52... 

The following table contains those naturally occurring furan derivatives which have recently been found, isolated, or elucidated. The name, origin, and structure are given in each case, and the references are kept to a minimum. 

Further naturally occurring furan compounds (without formulas given) ... 

The reaction was used to synthesize the naturally occurring furane perillene (2) from the ketone (I). 

The total synthesis of a naturally occurring furan fatty acid [21] has been described recently in which mercury (ll)-catalyzed isomerization of 2-(l,2-oxiranylcyclododecyl)-3-nonyn-2-ol was used as presented in Scheme 7 (88). 

Florentino HQ, Hemandez-Benitez RI, Avina JA, Burgueno-Tapia E, Tamariz J (2011) Total synthesis of naturally occurring furan compounds 5- [(4-hydroxybenzyl)oxy]methyl -2-furaldehyde and pichiafuran C. Synthesis 1106-1112... 

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