The Nazarov reaction entails the electrocyclic closure of a conjugated pentadienyl cation to furnish a cyclopentenyl cation. In its conventional protocol, this intermediate is allowed to undergo elimination through loss of an adjacent proton, providing cyclopentenone products. This feature article describes a relatively new class of domino and cascade processes in which the mechanistic course of the Nazarov reaction is diverted at the point of the cyclopentenyl cation intermediate, collectively referred to as "interrupted Nazarov reactions." A variety of intra- or intermolecular nucleophiles, including silyl hydrides, alkenes, arenes, amines, halides, oxygen nucleophiles and azides, can capture the cation at one terminus, resulting in interesting polycyclic structures. 1,3-Dienes also trap the cyclopentenyl cation, but in this case via concerted [4 + 3]-cycloaddition to give keto-bridged cyclooctenes. An alternative method for generating the pentadienyl cyclization precursor from dichlorocyclopropanes rather than cross-conjugated dienones is also discussed, along with some novel trapping processes.

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Facilitated hexose transporters (GLUTs) mediate the transport of hexoses and other substrates across the membranes of numerous cell types, and while some are expressed ubiquitously (e.g., GLUT1), others are more tissue specific (e.g., GLUT5). These properties have been exploited for the imaging of cancer cells by the use of hexose based probes, including fluorinated hexose derivatives for use with positron emission tomography (PET). However, design of new probes has been hampered by a limited understanding of how GLUT transporters interact with their substrates at the molecular level. Two fluorinated fructose surrogates designed for uptake by the GLUT5 transporter are described here: 3-deoxy-3-fluoro-D-fructose (3-FDF) and 1-deoxy-1-fluoro-2,5-anhydromannitol (1-FDAM). Synthesis (both cold and radiolabeled) and in vitro analysis of their transport characteristics in two breast cancer cell lines (EMT-6 and MCF-7) expressing GLUT5 are detailed. Both analogues are readily taken up into both cancer cell lines, with uptake mediated primarily by GLUT5. They also have low IC50 values, indicating a high affinity for the transporter, suggesting that the uptake of these probes would be unaffected by endogenously circulating fructose. Selective uptake by GLUT5 was also demonstrated in Xenopus oocytes. Finally, these results are the first demonstration that a hexose existing predominantly in the pyranose ring structure (3-FDF) is transported by GLUT5, strongly suggesting that this transporter can handle both furanose and pyranose forms of fructose.