C-C Coupling through Nitrogen Deletion: Application to Library Synthesis.

Invited for the cover of this issue are Oleksandr Grygorenko and his Ukrainian colleagues at Enamine Ltd., Taras Shevchenko National University of Kyiv, National Academy of Sciences of Ukraine, and ChemSpace, as well as Mark Levin at the University of Chicago. The image depicts application of a nitrogen-deleting anomeric amide to parallel C(sp3 )-C(sp3 ) coupling. Read the full text of the article at 10.1002/chem.202203470.

C-C Coupling through Nitrogen Deletion: Application to Library Synthesis.

A protocol for parallel C(sp3 )-C(sp3 ) coupling of (hetero)aromatic aldehydes and (hetero)arylmethyl amines based on a reductive amination - "nitrogen deletion" reaction sequence has been developed. After preliminary validation experiments, an illustrative compound library of 25 members was prepared with 76 % synthetic efficiency. The estimated chemical space accessible by the proposed approach covers almost 600 000 representatives that are scarcely represented in current compound databases.

Building the Housane: Diastereoselective Synthesis and Characterization of Bicyclo[2.1.0]pentane Carboxylic Acids.

An approach to 1,3-disubstitued bicyclo[2.1.0]pentane (housane) derivatives was developed. The method relied on lithium bis(trimethylsilyl)amide-mediated intramolecular cyclization of trisubstitued cyclopentane carboxylates bearing a leaving group (at the C-4 position) and an additional substituent (at the C-3 atom), in turn synthesized from cyclopent-3-ene carboxylate. The synthetic sequence allowed for the preparation of both cis- and trans-1,3-disubstituted housane-1-carboxylic acids in diastereoselective manner on up to 80 g scale. In particular, bicyclic γ-amino acids-γ-aminobutyric acid analogues-were synthesized. It was shown that the bicyclo[2.1.0]pentane did not significantly affect pKa of the corresponding derivatives and slightly increased their hydrophilicity (by 0.07-0.25 Log P units) as compared to cyclopentane. X-ray diffraction studies showed that cis- and trans-1,3-disubstituted housanes can be considered as flattened analogues of the corresponding cyclopentane derivatives with fixed envelope conformation of the five-membered ring.