Carbamoyl pyridone HIV-1 integrase inhibitors 3. A diastereomeric approach to chiral nonracemic tricyclic ring systems and the discovery of dolutegravir (S/GSK1349572) and (S/GSK1265744).

We report herein the discovery of the human immunodeficiency virus type-1 (HIV-1) integrase inhibitors dolutegravir (S/GSK1349572) (3) and S/GSK1265744 (4). These drugs stem from a series of carbamoyl pyridone analogues designed using a two-metal chelation model of the integrase catalytic active site. Structure-activity studies evolved a tricyclic series of carbamoyl pyridines that demonstrated properties indicative of once-daily dosing and superior potency against resistant viral strains. An inherent hemiaminal ring fusion stereocenter within the tricyclic carbamoyl pyridone scaffold led to a critical substrate controlled diastereoselective synthetic strategy whereby chiral information from small readily available amino alcohols was employed to control relative and absolute stereochemistry of the final drug candidates. Modest to extremely high levels of stereochemical control were observed depending on ring size and position of the stereocenter. This approach resulted in the discovery of 3 and 4, which are currently in clinical development.

Carbamoyl pyridone HIV-1 integrase inhibitors. 2. Bi- and tricyclic derivatives result in superior antiviral and pharmacokinetic profiles.

This work is a continuation of our initial discovery of a potent monocyclic carbamoyl pyridone human immunodeficiency virus type-1 (HIV-1) integrase inhibitor that displayed favorable antiviral and pharmacokinetic properties. We report herein a series of bicyclic carbamoyl pyridone analogues to address conformational issues from our initial SAR studies. This modification of the core unit succeeded to deliver low nanomolar potency in standard antiviral assays. An additional hydroxyl substituent on the bicyclic scaffold provides remarkable improvement of antiviral efficacies against clinically relevant resistant viruses. These findings led to additional cyclic tethering of the naked hydroxyl group resulting in tricyclic carbamoyl pyridone inhibitors to address remaining issues and deliver potential clinical candidates. The tricyclic carbamoyl pyridone derivatives described herein served as the immediate leads in molecules to the next generation integrase inhibitor dolutegravir which is currently in late stage clinical evaluation.

Carbamoyl pyridone HIV-1 integrase inhibitors. 1. Molecular design and establishment of an advanced two-metal binding pharmacophore.

Our group has focused on expanding the scope of a two-metal binding pharmacophore concept to explore HIV-1 integrase inhibitors through medicinal chemistry efforts to design novel scaffolds which allow for improvement of pharmacokinetic (PK) and resistance profiles. A novel chelating scaffold was rationally designed to effectively coordinate two magnesium cofactors and to extend an aromatic group into an optimal hydrophobic pharmacophore space. The new chemotype, consisting of a carbamoyl pyridone core unit, shows high inhibitory potency in both enzymatic and antiviral assay formats with low nM IC50 and encouraging potency shift effects in the presence of relevant serum proteins. The new inhibitor design displayed a remarkable PK profile suggestive of once daily dosing without the need for a PK booster as demonstrated by robust drug concentrations at 24 h after oral dosing in rats, dogs, and cynomolgus monkeys.

Synthesis and antiviral activity of 7-benzyl-4-hydroxy-1,5-naphthyridin-2(1H)-one HIV integrase inhibitors.

The medicinal chemistry and structure-activity relationships for a novel series of 7-benzyl-4-hydroxy-1,5-naphthyridin-2(1H)-one HIV-integrase inhibitors are disclosed. Substituent effects were evaluated at the N-1, C-3, and 7-benzyl positions of the naphthyridinone ring system. Low nanomolar IC(50) values were achieved in an HIV-integrase strand transfer assay with both carboxylic ester and carboxamide groups at C-3. More importantly, several carboxamide congeners showed potent antiviral activity in cellular assays. A 7-benzyl substituent was found to be critical for potent enzyme inhibition, and an N-(2-methoxyethyl)carboxamide moiety at C-3 significantly reduced plasma protein binding effects in vitro. Pharmacokinetic data in rats for one carboxamide analogue demonstrated oral bioavailability and reasonable in vivo clearance.

3-Hydroxy-1,5-dihydro-pyrrol-2-one derivatives as advanced inhibitors of HIV integrase.

The two-metal binding model we previously reported as an inhibition mechanism of HIV integrase (HIV IN) produced a new direction in modification of 2-hydroxy-3-heteroaryl acrylic acid inhibitors (HHAAs). Here we present a novel series of HIV IN inhibitors having a 3-hydroxy-1,5-dihydro-pyrrol-2-one moiety (HDPO) as an advanced analog of HHAAs. This cyclic modification of the chelating region of HHAA produces a favorable configuration to coordinate two-metal ions in HIV IN, which consequently gave improvements in not only enzymatic assay but also antiviral cell based assay in many cases.

A platform for designing HIV integrase inhibitors. Part 2: a two-metal binding model as a potential mechanism of HIV integrase inhibitors.

We propose a two-metal binding model as a potential mechanism of chelating inhibitors against HIV integrase (HIV IN) represented by 2-hydroxy-3-heteroaryl acrylic acids (HHAAs). Potential inhibitors would bind to two metal ions in the active site of HIV IN to prevent human DNA from undergoing the integration reaction. Correlation of the results of metal (Mg(2+) and Mn(2+)) titration studies with HIV IN inhibition for a series of active and inactive compounds provides support for the model. Results suggest Mg(2+) is an essential cofactor for chelating inhibitors.

Total Synthesis of Terprenin, a Novel Immunosuppressive p-Terphenyl Derivative.

We achieved a total synthesis of terprenin, a novel potent immunoglobulin E antibody suppressant which was obtained from the fermentation broth of Aspergillus candidus RF-5672 and has a highly oxygenated p-terphenyl skeleton with a prenyloxy side chain. The key steps relied on the Suzuki reaction to construct the terphenyl skeleton and on regioselective halogenations to selectively combine the aromatic rings. The highly efficient and practical production of this important natural product offers promise for the development of a new type of antiallergic drug.

Total Synthesis of Terprenin, a Highly Potent and Novel Immunoglobulin E Antibody Suppressant.

Regioselective halogenations and Suzuki reactions ensure proper linkage of the aromatic rings in two total syntheses of terprenin (1). Both routes make it possible to prepare 1 efficiently and in large quantity.