Paul R. Hanson, University of Kansas, Lawrence, KS
The development of new synthetic strategies allowing for efficient asymmetric syntheses of complex biologically active targets, with minimal protecting group manipulations and chemical steps, is an enormous challenge in natural product synthesis. A powerful way of addressing this synthetic challenge is via convergent methodologies employing temporary tethering of two advanced intermediates, coupled with strategies exploiting molecular symmetry. Historically, silicon has been the most widely used tether, in which innate attributes have served as the cornerstone of several elegant synthetic strategies. In contrast, use of phosphorus-based tethers (P-tethers) has been relatively limited, a surprising observation when one considers the potential of phosphorus tethers to mediate both di- and tripodal coupling and provide multivalent activation via inherent leaving group abilities possessed by phosphate. While there are no major conceptual or theoretical barriers toward using P-tethers, methodologies dependent on these potential advantages have not been developed. However, recent studies from our laboratories provide compelling experimental evidence that supports the validity of the following relatively unexplored areas of phosphate chemistry, namely: (i) the use of temporary phosphate tethers in advanced synthesis, (ii) subsequent selective cleavage reactions that exploit latent leaving group ability and (iii) additional nucleophilic behavior of phosphate esters/acids inherent to phosphates and analogs thereof. Overall, these attributes provide a powerful platform of unexplored reactivity that when fully harnessed will provide access to differentiated polyol synthons for use in the synthesis of biologically active targets.
Web Page:
www.chem.ku.edu/PHansonGroup/
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