engleski

Photochemical approach to fused furan and thiophene polycyclic structures

Formation of the bicyclic structures has received much attention since they represent the basic framework of numerous important biologically active natural compounds or their metabolites. Their skeleton has also proved to be useful reactive intermediate in various stereoselective transformations making these derivatives powerful building blocks in organic synthesis [1]. Thus, in aim to prepare new bicyclic furan and thiophene derivatives, 2-[2-(2-ethenylphenyl)ethenyl]furan (1a) [2], 2-[2-(2-ethenylphenyl)ethenyl]thiophene (1b) [3], 3-[2-(2-ethenylphenyl)ethenyl]furan (2a) and 3-[2-(2-ethenylphenyl)ethenyl]thiophene (2b) were synthesized. These starting compounds upon irradiation convert to bicyclo[3.2.1.]octadiene (3, 4) and bicyclo[2.1.1.]hexene (5) structures [4] as main products, by [2+2] cycloaddition via biradical mechanism. This is an example of elegant and direct synthesis of complex polycyclic compounds.

oxygen heterocycles; sulfur heterocycles; furan; thiophene; photochemistry; photocycloaddition; synthesis

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