Ligand-free Suzuki coupling of arylboronic acids with methyl (E)-4-bromobut-2-enoate: synthesis of unconventional cores of HIV-1 protease inhibitors

Diastereoselective Synthesis of the HIV Protease Inhibitor Darunavir and Related Derivatives via a Titanium Tetrachloride-Mediated Asymmetric Glycolate Aldol Addition Reaction

Darunavir is a potent HIV protease inhibitor that has been established as an effective tool in the fight against the progression of HIV/AIDS in the global community. The successful application of this drug has spurred the development of derivatives wherein strategic regions (e.g., P1, P1', P2, and P2') of the darunavir framework have been structurally modified. An alternate route for the synthesis of darunavir and three related P1 and P1' derivatives has been developed. This synthetic pathway involves the use of a Crimmins titanium tetrachloride-mediated oxazolidine-2-thione-guided asymmetric glycolate aldol addition reaction. The resultant aldol adduct introduces the P1 fragment of darunavir via an aldehyde. Transamidation with a selected amine (isobutylamine or 2-ethyl-1-butylamine) to cleave the auxiliary yields an amide wherein the P1' component is introduced. From this stage, the amide is reduced to the corresponding β-amino alcohol and the substrate is then bis-nosylated to introduce the requisite p-nitrobenzenesulfonamide component and activate the secondary alcohol for nucleophilic substitution. Treatment with sodium azide yielded the desired azides, and the deprotection of the p-methoxyphenoxy group is achieved with the use of ceric ammonium nitrate. Finally, hydrogenation to reduce both the aniline and azide functionalities with concurrent acylation yields darunavir and its derivatives.

Total synthesis of griseusins and elucidation of the griseusin mechanism of action

An efficient divergent synthesis of griseusins enabled SAR studies, mechanistic elucidation and evaluation in an axolotl tail regeneration model.

A divergent modular strategy for the enantioselective total synthesis of 12 naturally-occurring griseusin type pyranonaphthoquinones and 8 structurally-similar analogues is described. Key synthetic highlights include Cu-catalyzed enantioselective boration–hydroxylation and hydroxyl-directed C–H olefination to afford the central pharmacophore followed by epoxidation–cyclization and maturation via diastereoselective reduction and regioselective acetylation. Structural revision of griseusin D and absolute structural assignment of 2a,8a-epoxy-epi-4′-deacetyl griseusin B are also reported. Subsequent mechanistic studies establish, for the first time, griseusins as potent inhibitors of peroxiredoxin 1 (Prx1) and glutaredoxin 3 (Grx3). Biological evaluation, including comparative cancer cell line cytotoxicity and axolotl embryo tail inhibition studies, highlights the potential of griseusins as potent molecular probes and/or early stage leads in cancer and regenerative biology.

Palladium-catalyzed stereospecific cross-coupling of enantioenriched allylic alcohols with boronic acids

In the presence of 2.5 mol% Pd2(dba)3-TMEDA (1 : 4), a range of enantioenriched allylic alcohols smoothly coupled with boronic acids in a highly regioselective fashion with inversion of configuration to afford structurally diverse alkenes in good yields with perfect retention of ee.

Pd-catalyzed ligand-free Suzuki reaction of β-substituted allylic halides with arylboronic acids in water

The combination of Pd(TFA)₂ and KOH could efficiently catalyze the reaction of β-substituted allylic halides with arylboronic acids in water.