Sculpting the Bicyclo[3.1.0]hexane Template of Carbocyclic Nucleosides to Improve Recognition by Herpes Thymidine Kinase

The replacement of the furanose ring by a cyclopentane in nucleosides generates a group of
analogues known generically as carbocyclic nucleosides. These compounds have increased chemical and
enzymatic stability due to the absence of a true glycosyl bond that characterizes conventional nucleosides.
The additional fusion of a cyclopropane ring to the cyclopentane produces a bicyclo[3.1.0]hexane system
that depending on its location relative to the nucleobase is able to lock the embedded cyclopentane ring
into conformations that mimic the typical north and south conformations of the furanose ring in conventional
nucleosides. These bicyclo[3.1.0]hexane templates have already provided important clues to differentiate
the contrasting conformational preferences between kinases and polymerases. Herein, we describe the
design, synthesis, and phosphorylation pattern of a new bicyclo[3.1.0]hexane thymidine analogue that seems
to possess an ideal spatial distribution of pharmacophores for an optimal interaction with herpes simplex
1 thymidine kinase. The bicyclo[3.1.0]hexane template represents a privileged rigid template for sculpting
other carbocyclic nucleosides to meet the demands of specific receptors.