Reactions of α-imino ketones derived from arylglyoxals with (trifluoromethyl)trimethylsilane; a new route to β-amino-α-trifluoromethyl alcohols

Chemoselective Synthesis of α-Tertiary Hydroxy Oximes via Photochemical 1,3-Boronate Rearrangement

Tertiary alcohols with adjacent nucleophilic labile groups are prevalent in bioactive molecules but are challenging to synthesize. Herein we introduce a direct, protecting group-free method to access α-tertiary hydroxy oximes via photochemical 1,3-boronate rearrangement. This reaction delivers high yields (up to 94%) using readily available boronic acids, is scalable to gram quantities, and allows for further derivatization to other nitrogen-containing molecules.

Construction of trifluoromethylated quaternary stereocenters via p-quinone methides

Development of a new synthetic method for the construction of quaternary centers with a CF₃ group was realized by way of 1,6-addition of various nucleophiles to highly reactive δ-trifluoromethylated p-quinone methides generated in situ.

Antiviral agents derived from novel 1-adamantyl singlet nitrenes

BACKGROUND

Amantadine constitutes an interesting, diamond crystal lattice-shaped, antivirally active amine with an inhibitory effect on influenza A viruses causing common 'flu' in humans. Unfortunately, amantadine forfeited most of its therapeutic potential because of resistance development in recent influenza A virus isolates. The antiviral efficacy of amantadine congeners can be chemically modified, resulting in re-constitution, improvement and/or extension of antiviral activities mediated by amino-adamantyls.

METHODS

Newly synthesized compounds were evaluated towards HIV type-1 (HIV-1) replication in primary human lymphocytes. One N-phenacyl amantadine derivative was investigated for inhibiting the in vitro replication of respiratory viruses (influenza A viruses, influenza B virus, human parainfluenza virus type 3 and severe acute respiratory syndrome coronavirus).

RESULTS

Two ketone-stabilized 1-adamantyl singlet nitrenes were discovered serendipitously. To our best knowledge these are the first persistently stable nitrenes to be reported. Their structure was proved by determining the X-ray single crystal structure of one hydrolytic elaboration product. This salt adduct revealed an incommensurately modulated crystal structure, which was solved by extensive computational refinement. We could show that ketone-stabilized 1-adamantyl singlet nitrenes are versatile synthons for the synthesis of antiviral drug candidates. An amantadine-folate conjugate was inhibitory on HIV-1 replication in primary human lymphocytes, and one N-phenacyl amantadine derivative was inhibitory towards low pathogenic avian influenza A virus (H5N1) replication in vitro.

CONCLUSIONS

These results indicate that the aromatic-aliphatic ketone-stabilized 1-adamantyl singlet nitrenes, beyond being of fundamental interest in organic chemistry, represent versatile synthons for the synthesis of new amantadine-related potentially antiviral drugs.