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.

Synthesis of Fused sp-Enriched Imidazoles.

A synthetic approach to imidazoles annulated to saturated six-membered cycles featuring S, SO, NH, NCbz was developed. It was achieved by combining the Neber rearrangement and the Marckwald reaction. The Neber rearrangement applied to cyclic ketones allowed us to prepare in hundred gram quantities previously unknown α-amino ketones.

Supramolecular architecture of theophylline polymorphs, monohydrate and co-crystals with iodine: study from the energetic viewpoint.

The regularities of crystal structure organization were thoroughly studied in all to date known polymorphic modifications of theophylline (THP) using an energetic approach. The monohydrate and a co-crystal of theophylline with one half equivalent of an iodine molecule were similarly investigated. The calculations of pairwise interaction energies have showed that the crystals studied can be divided into two groups according to their basic structural motifs: or .

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations.

By one-pot four- and three-component Ugi reactions involving convertible isocyanides and unexplored pyrrole-containing β-chlorovinylaldehyde, a small library of 20 bisamides with unusual behavior in post-Ugi transformations was prepared and characterized. Surprisingly, a well-documented approach to obtain peptide-containing carboxylic acids through acid hydrolysis of the convertible isocyanide moiety in the Ugi bisamides proceeded in an unexpected manner in our case, leading to the formation of derivatives of amides of heterylidenepyruvic acid. An optimized synthetic protocol for this transformation was elaborated and a plausible sequence involving the elimination of the 2-chloroacetamide moiety and the conversion of the β-chlorovinyl fragment into a vinyl one is provided.

3-Substituted 6-Azabicyclo[3.1.1]heptanes: Nonclassical Piperidine Isosteres for Drug Discovery.

Advanced analogs of piperidine and smaller homologues of tropane─3-substituted 6-azabicyclo[3.1.1]heptanes─were synthesized on a large scale using readily available bulk reagents.