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A synthetic strategy to provide two late-stage intermediates for the synthesis of diverse analogues of ROMK inhibitors for the treatment of hypertension and heart failure is described. Key transfor...

A six-step route starting from a readily available vinyl boronate was identified to produce an enantioenriched cyclopropanol in an overall 16% yield. Key steps involve the use of lithium acetylide-ethylene diamine complex 5 and an enzymatic resolution of a racemic cyclopropanol acetate. Process safety considerations surrounding the use of 5 were examined, and an improved procedure is described which was safely demonstrated at multikilogram scale.

Biocatalytic Boost Enzymes tend to direct reactions toward specific products much more selectively than synthetic catalysts. Unfortunately, this selectivity has evolved for cellular purposes and may not promote the sorts of reactions chemists are seeking to enhance (see the Perspective by Lutz ). Siegel et al. (p. 309 ) now describe the design of enzymes that catalyze the bimolecular Diels-Alder reaction, a carbon-carbon bond formation reaction that is central to organic synthesis but unknown in natural metabolism. The enzymes display high stereoselectivity and substrate specificity, and an x-ray structure of the most active enzyme confirms that the structure matches the design. Savile et al. (p. 305 , published online 17 June) applied a directed evolution approach to modify an existing transaminase enzyme so that it recognized a complex ketone in place of its smaller native substrate, and could tolerate the high temperature and organic cosolvent necessary to dissolve this ketone. This biocatalytic reaction improved the production efficiency of a drug that treats diabetes.

The use of ambient pressure desorption ionization mass spectrometry for the rapid analytical support of process and pharmaceutical development is demonstrated. The ability of direct analysis in real time (DART) technology to analyze both active pharmaceutical ingredients (APIs) and intermediates without sample preparation or the development of LC-based separations provided critical experimental results with minimal time required for method development. The utility and versatility of DART is shown for applications such as degradation studies, analysis of high-throughput catalyst screens, preparative-scale chromatography fractions, and impurity determination.

The development of practical and efficient syntheses of the potent non-nucleoside reverse transcriptase inhibitors 1 and 2 is described. The preparation of 1 proceeded in four synthetic steps and in 48% overall yield from 3. The long-term synthesis of 2 proceeded in nine synthetic steps and in 47% overall yield from commercially available 2,6-diflurorpyridine. The route to 2 was highlighted by the three-step synthesis of intermediate 22 and the high yielding coupling between 18 and phenol 8. The overall sequence required no chromatography and has successfully been utilized for the manufacture of 2 on large scale.

Two applications for the asymmetric reduction of activated alkenes employing isolated enoate reductases are reported. A series of α,β-unsaturated nitriles were shown to be converted to the optically active nitrile products in high yields and excellent enantioselectivities (up to 99% ee). In addition, the reduction of 2,3-disubstituted cyclopentenones was shown to provide almost exclusively trans -2,3-disubstituted cyclopentanones in high yield and enantiopurity (94% ee).

Enantiocomplementary R- and S-cyanohydrins with >93% ee were synthesized through the hydrocyanation of 3-pyridinecarboxaldehyde in >65% yield. Hydroxynitrile lyases (HNLs) from cassava and almond were used in commercially available cross-linked enzyme aggregate (CLEA) forms to catalyze the reactions and produce material with optical purities significantly greater than has been reported previously. The use of a dichloromethane reaction system with enzyme aggregates and free hydrogen cyanide was crucial in improving cyanohydrin stereoselectivity through minimizing background racemic cyanide addition and enzyme-catalyzed racemization of the product.

The synthesis of ( R )- and ( S )-cyanohydrins from a range of aromatic methyl and ethyl ketones, including the first examples from substituted variants of phenylacetone, benzylacetone and propiophenone, is described. Commercially available hydroxynitrile lyase (HNL) enzymes were used to catalyze the asymmetric addition of cyanide to the ketones, including the first successful application of the flax HNL (LuHNL) to the synthesis of any aromatic ( S )-cyanohydrin. Both reaction yields and stereoselectivities were shown to be influenced by the carbon chain length between the ketone and phenyl functional groups, and the type of aromatic substitution present on the starting material. Substrates converted with the greatest degree of productivity and selectivity were phenylacetones with large, electron withdrawing meta -substituents, such as 3-Cl, 3-Br and 3-CF 3 phenylacetones, from which cyanohydrins are formed with 93–99% ee and 61–71% yield.

Two syntheses of the title compound 1 were developed based on different approaches for installing the oxazole ring moiety. Formation and dehydration of ketoamide was initially used and scaled up to afford 1 on several kilogram scale, then oxazolyl anion/iminium coupling reaction was developed for a more convergent approach.

Chromatography plays a vital role in supporting preclinical pharmaceutical development, whether in providing assays for purity determinations, preparative separation of small amounts of intermediates for route selection studies, or purification of bulk drug substances on multikilogram scale. All three approaches are illustrated in the recent development of a candidate HIV protease inhibitor in these laboratories. Chiral supercritical fluid chromatography (SFC) on the hundreds-of-milligrams scale afforded an enantiopure intermediate to facilitate early synthetic studies, HPLC on the tens-of-grams scale provided purified material for use in salt form investigations, and HPLC using a 30 cm column was used to purify 5.6 kg of a key intermediate to provide material for early preclinical evaluations.

An efficient stereoselective preparation of HIV protease inhibitor (+)-1 was synthesized on multi-kilogram scale in 16 steps without the use of chromatography. The key steps include the diastereoselective alkylation of acetal 3, a diastereoselective iodo-hydroxylation to generate epoxide 6, and a reductive amination in the final coupling step that averts a non-productive cyclic aminal intermediate.

[reaction: see text] Trifluoropropanoic acid reacts with 1 equiv of POCl3 in DMF to generate the trifluoromethyl enamine (7). At this stage, two reaction manifolds are available. The expected reaction with additional POCl3 generates the 2-trifluoromethyl vinamidinium salt (3c). However, thermally driven loss of fluoride generates an iminium ion, which sets the stage for a [2 + 2] cycloaddition to ultimately generate the dimethylaminomethylene vinamidinium salt (1).

A multi-kilogram scale synthesis of the orally efficacious thrombin inhibitor 1 has been achieved via construction of the pyrazinone core from an unsymmetric oxalic diamide. Key features include judicious choice of reagents to minimize side products, a key ruthenium catalyzed oxidation, and development of reaction conditions amenable to large-scale synthesis.

The discovery of 1,3,8-triazaspiro[4.5]decane-2,4-diones (spirohydantoins) as a structural class of pan-inhibitors of the prolyl hydroxylase (PHD) family of enzymes for the treatment of anemia is described. The initial hit class, spirooxindoles, was identified through affinity selection mass spectrometry (AS-MS) and optimized for PHD2 inhibition and optimal PK/PD profile (short-acting PHDi inhibitors). 1,3,8-Triazaspiro[4.5]decane-2,4-diones (spirohydantoins) were optimized as an advanced lead class derived from the original spiroindole hit. A new set of general conditions for C-N coupling, developed using a high-throughput experimentation (HTE) technique, enabled a full SAR analysis of the spirohydantoins. This rapid and directed SAR exploration has resulted in the first reported examples of hydantoin derivatives with good PK in preclinical species. Potassium channel off-target activity (hERG) was successfully eliminated through the systematic introduction of acidic functionality to the molecular structure. Undesired upregulation of alanine aminotransferese (ALT) liver enzymes was mitigated and a robust on-/off-target margin was achieved. Spirohydantoins represent a class of highly efficacious, short-acting PHD1-3 inhibitors causing a robust erythropoietin (EPO) upregulation in vivo in multiple preclinical species. This profile deems spirohydantoins as attractive short-acting PHDi inhibitors with the potential for treatment of anemia.

This work established the idea that a halogen atom, such as bromine, will act as a control element in the regiospecific formation of a new carbon-carbon bond. The addition of the electron-rich end of a transoid diene to a bromojuglone derivative occurred exclusively at the unsubstituted carbon of the quinone. Thus, 2,2-dimethyl-4-methoxy-6-methylene-1,3-dioxa-2-sila-4-cyclohexene (3) and either 2- or 3-bromo-5-hydroxy-1,4-naphthoquinone (1 or 2) afforded the adducts 19 or 20 in 57% or 71% yield. Similarly, 2,2-dimethyl-6-methylene-4-(trimethylsiloxy)-1,3-diox-4-ene (4) and 1 gave 21 in 77% yield

A dependable high yielding palladium catalyzed aryl bromide cyanation procedure has been developed. The optimized cyanation features extremely low levels of palladium and DPPF ligand.

A dependable high yielding palladium catalyzed aryl bromide cyanation procedure has been developed. The optimized cyanation features extremely low levels of palladium and DPPF ligand.

m-Butyl 4-chlorophenyl sulfide R 4-Chlorophenol I 4-Chlorophenyl trifluoromethanesulfonate P m-Butyl 4-chlorophenyl sulfide Keywords: sulfur compounds; halogen compounds, fluorine compounds; halogen compounds, chlorine compounds; sulfonation, o-sulfonation; pyridine; n-butyl 4-chlorophenyl sulfide; replacement reactions, sulfonate by sulfur; arylation

A multi-kilogram scale synthesis of the orally efficacious thrombin inhibitor 1 has been achieved via construction of the pyrazinone core from an unsymmetric oxalic diamide. Key features include judicious choice of reagents to minimize side products, a key ruthenium catalyzed oxidation, and development of reaction conditions amenable to large-scale synthesis.