Tetrakis furan, synthesis

When the chiral catalyst tetrakis(binaphtholphosphate)dirhodium was used, moderate enantiomeric excess (50%) was obtained in cycloaddition reactions with furans and dihydrofurans (359). This method has been applied to the synthesis of several natural products that contain fused furan rings, e.g., the human platelet... 

Dewar tetrakis(trifluoromethyl)thiophene, (59), has served as a dieneophile (dipolarophile) in several cycloadditions. Diels-Alder reaction of (59) with butadiene <8icci289> and pyrrole (82JA847) has served as the starting point for the synthesis of 1,2,3,8-tetrakis(trifluoromethyl)cyclooctatetraene (60) and tetrakis(trifluoromethyl)Dewar furan (61), respectively, as illustrated in Scheme 20. It is noteworthy that (61) was unattainable by direct photolysis of the substituted furan. Moreover, (59) served as a common precursor for the preparation of tetrakis- (80JA6633) and penta-<83JA3563> (trifluoromethyl)cyclopentadienides (64) and (65), respectively (Scheme 21). Accordingly, photolysis... 

So far, the formation of valence-bond isomers by photolysis has mainly been discussed. Tetrakis(trifluoromethyl) Dewar thiophene is stable at room temperature and was used for the synthesis of Dewar pyrroles, a Dewar furan, and other interesting compounds from the standpoint of the structural chemistry. In this section, some of these reactions will be discussed. 

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