2-Oxabicyclo[2.2.2]octane as a new bioisostere of the phenyl ring

Silver-Enabled Cycloaddition of Bicyclobutanes with Isocyanides for the Synthesis of Polysubstituted 3-Azabicyclo[3.1.1]heptanes

Synthesis of bicyclic scaffolds has emerged as an important research topic in modern drug development because they can serve as saturated bioisosters to enhance the physicochemical properties and metabolic profiles of drug candidates. Here we report a remarkably simple silver-enabled strategy to access polysubstituted 3-azabicyclo[3.1.1]heptanes in a single operation from readily accessible bicyclobutanes (BCBs) and isocyanides. The process is proposed to involve a formal (3+3)/(3+2)/retro-(3+2) cycloaddition sequence. This novel protocol allows for rapid generation of molecular complexity from simple starting materials, and the products can be easily derivatized, further enriching the BCB cycloaddition chemistry and the growing set of valuable sp3-rich bicyclic building blocks.

2-Oxabicyclo[2.1.1]hexanes: Synthesis, Properties, and Validation as Bioisosteres of ortho- and meta-Benzenes

We have developed a general and practical approach towards 2-oxabicyclo[2.1.1]hexanes with two and three exit vectors via an iodocyclization reaction. The obtained compounds have been easily converted into the corresponding building blocks for use in medicinal chemistry. 2-Oxabicyclo[2.1.1]hexanes have been incorporated into the structure of five drugs and three agrochemicals, and validated biologically as bioisosteres of ortho- and meta-benzenes.

Spiro[3.3]heptane as a Saturated Benzene Bioisostere

The spiro[3.3]heptane core, with the non-coplanar exit vectors, was shown to be a saturated benzene bioisostere. This scaffold was incorporated into the anticancer drug sonidegib (instead of the meta-benzene), the anticancer drug vorinostat (instead of the phenyl ring), and the anesthetic drug benzocaine (instead of the para-benzene). The patent-free saturated analogs obtained showed a high potency in the corresponding biological assays.