Discovery and optimization of pyrazolopyrimidine sulfamates as ATG7 inhibitors.

Autophagy is postulated to be required by cancer cells to survive periods of metabolic and/or hypoxic stress. ATG7 is the E1 enzyme that is required for activation of Ubl conjugation pathways involved in autophagosome formation. This article describes the design and optimization of pyrazolopyrimidine sulfamate compounds as potent and selective inhibitors of ATG7. Cellular levels of the autophagy markers, LC3B and NBR1, are regulated following treatment with these compounds.

Optimization of tetrahydronaphthalene inhibitors of Raf with selectivity over hERG.

Investigations of a biaryl ether scaffold identified tetrahydronaphthalene Raf inhibitors with good in vivo activity; however these compounds had affinity toward the hERG potassium channel. Herein we describe our work to eliminate this hERG activity via alteration of the substituents on the benzoic amide functionality. The resulting compounds have improved selectivity against the hERG channel, good pharmacokinetic properties and potently inhibit the Raf pathway in vivo.

Design and optimization of potent and orally bioavailable tetrahydronaphthalene Raf inhibitors.

Inhibition of mutant B-Raf signaling, through either direct inhibition of the enzyme or inhibition of MEK, the direct substrate of Raf, has been demonstrated preclinically to inhibit tumor growth. Very recently, treatment of B-Raf mutant melanoma patients with a selective B-Raf inhibitor has resulted in promising preliminary evidence of antitumor activity. This article describes the design and optimization of tetrahydronaphthalene-derived compounds as potent inhibitors of the Raf pathway in vitro and in vivo. These compounds possess good pharmacokinetic properties in rodents and inhibit B-Raf mutant tumor growth in mouse xenograft models.

Gold-catalyzed cycloisomerization of N-Propargylindole-2-carboxamides: application toward the synthesis of lavendamycin analogues.

A series of N-propargylindole-2-carboxamides were found to undergo a AuCl 3-catalyzed cycloisomerization to give beta-carbolinones in high yield. The corresponding beta-chlorocarboline derivative was prepared and used for Pd(0)-catalyzed cross-coupling chemistry directed toward the synthesis of lavendamycin analogues.

The Rhodium(II) Carbenoid Cyclization-Cycloaddition Cascade of alpha-Diazo Dihydroindolinones for the Synthesis of Novel Azapolycyclic Ring Systems.

Tandem carbonyl ylide formation-1,3-dipolar cycloaddition of alpha-diazo N-acetyl-tetrahydro-beta-carbolin-1-one derivatives occur efficiently in the presence of a dirhodium catalyst to afford bimolecular cycloadducts in high yield. The Rh(II)-catalyzed reaction also takes place intramolecularly to give products derived from trapping of the carbonyl ylide dipole with a tethered alkene. The power of the intramolecular cascade sequence is that it rapidly assembles a pentacyclic ring system containing three new stereocenters and two adjacent quaternary centers stereospecifically in a single step and in high yield.

General access to the vinca and tacaman alkaloids using a Rh(II)-catalyzed cyclization/cycloaddition cascade.

The total synthesis of several members of the vinca and tacaman classes of indole alkaloids has been accomplished. The central step in the synthesis consists of an intramolecular [3+2]-cycloaddition reaction of an alpha-diazo indoloamide which delivers the pentacyclic skeleton of the natural product in excellent yield. The acid lability of the oxabicyclic structure was exploited to establish the trans-D/E ring fusion of (+/-)-3H-epivincamine (3). Finally, a base induced keto-amide ring contraction was utilized to generate the E-ring of the natural product. A variation of the cascade sequence of reactions used to synthesize (+/-)-3H-epivincamine was also employed for the synthesis of the tacaman alkaloids (+/-)-tacamonine and (+/-)-apotacamine.

Substitution and cyclization reactions involving the quasi-antiaromatic 2H-indol-2-one ring system.

The quasi-antiaromatic 2H-indol-2-one ring system is readily generated by treating a 3-hydroxy-substituted 1,3-dihydroindol-2-one with a Lewis acid. Stepwise addition of various pi-nucleophiles to the highly reactive 2H-indol-2-one system occurs smoothly to afford substituted oxindoles. The cyclization was also carried out in an intramolecular fashion to give spiro-substituted oxindoles in good yield.

Synthesis of (+/-)-3H-epivincamine via a Rh(II)-triggered cyclization/cycloaddition cascade.

A synthesis of (+/-)-3H-epivincamine is reported. Important steps include (1) a Rh(II)-catalyzed intramolecular [3+2]-cycloaddition of an alpha-diazo indolo amide, (2) a reductive ring opening of the cycloadduct, (3) a decarboethoxylation reaction, and (4) a base-induced keto-amide ring contraction.

Synthesis of the western half of the lolicines and lolitrems.

[reaction: see text] The synthesis of the highly substituted indole portion of the complex tremorgenic natural products lolicine A and B is presented. The Diels-Alder reaction of a quinone monoimine enables the synthesis of an appropriately substituted indole. The key step in the synthesis is a tandem isopropenyl cuprate addition/aldol cyclocondensation which provides the necessary functionality for elaboration to the 2,2,5,5-tetramethyltetrahydrofuran.

Synthesis and cross-coupling reactions of substituted 5-triflyloxyindoles.

N-arylsulfonyl quinone monoimines undergo smooth cycloadditions in a [4+2] sense to yield the expected cycloadducts. The crude cycloadducts, when subjected to a short series of simple transformations, produce synthetically useful quantities of 5-triflyloxyindoles in excellent overall yields. Such compounds are excellent participants in cross-coupling chemistry.