Physicochemical and Biological Evaluation of gem-Difluorinated Saturated Oxygen Heterocycles as Bioisosteres for Drug Discovery.

A comprehensive study on the physicochemical properties of gem-fluorinated O-heterocyclic substituents is reported. Systematic additive effects of introducing O- and gem-CF group introduction on acidic properties (pK) of the corresponding carboxylic acids/protonated primary amines were demonstrated. The impact of the O/CF moieties on lipophilicity (LogP) was found to be complex; significant mutual influence of the corresponding polar moieties governed the compound's overall properties in this case.

"Angular" Spirocyclic Azetidines: Synthesis, Characterization, and Evaluation in Drug Discovery.

The previously neglected "angular" spirocyclic azetidines have been synthesized, characterized, and validated in drug discovery. We have shown that these compounds could act as bioisosteres for common saturated six-membered heterocycles. Their incorporation into the structure of the anticancer drug Sonidegib (instead of morpholine), and Danofloxacine (instead of piperazine) provided novel patent-free analogs with similar physicochemical properties and high activity.

CF-Cyclobutanes: Synthesis, Properties, and Evaluation as a Unique -Butyl Group Analogue.

Isosteric replacement of functional groups is an emerging strategy for optimizing bioactive molecules in drug discovery. -Butyl group is a particularly important moiety, yet its isosteric replacement with 1-trifluoromethyl-cyclobutyl group has been rather neglected. To enable the advance of this molecular fragment in drug discovery programs, we report the synthesis of over 30 small-molecule building blocks featuring the trifluoromethyl-cyclobutyl fragment, achieved by reacting sulfur tetrafluoride with cyclobutylcarboxylic acids on a gram-to-multigram scale.

4-Azaspiro[2.3]hexane, an Overlooked Piperidine Isostere: Multigram Synthesis and Physicochemical and Structural Evaluation.

An expedient approach to the synthesis of 4-azaspiro[2.3]hexane derivatives is described. The synthetic scheme consists of Tebbe olefination of -Boc-protected 2-azetidinone (including the first use of the deuterated Petasis reagent CpTi(CD) in the building block preparation) and cyclopropanation of the resulting intermediate.

3,3-Difluorooxetane-A Versatile Functional Group for Bioisosteric Replacements in Drug Discovery.

Functional group (FG) is one of the cornerstone concepts in organic chemistry and related areas. The wide spread of bioisosterism ideas in medicinal chemistry and beyond caused a striking rise in demand for novel FGs with a defined impact on the developed compound properties. In this work, the evaluation of the 3,3-difluorooxetane unit (3,3-diFox) as a functional group for bioisosteric replacements is disclosed.

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.

1,2-Disubstituted bicyclo[2.1.1]hexanes as saturated bioisosteres of -substituted benzene.

Bicyclo[2.1.1]hexanes have been synthesized, characterized, and biologically validated as saturated bioisosteres of the -substituted benzene ring.

1-Azaspiro[3.3]heptane as a Bioisostere of Piperidine.

1-Azaspiro[3.3]heptanes were synthesized, characterized, and validated biologically as bioisosteres of piperidine. The key synthesis step was thermal [2+2] cycloaddition between endocyclic alkenes and the Graf isocyanate, ClO S-NCO, to give spirocyclic β-lactams.