A Synthesis of l-Vancosamine Derivatives from Non-Carbohydrate Precursors by a Short Sequence Based on the Marshall, McDonald, and Du Bois Reactions

The carbamate-protected l-vancosamine glycal, viewed as a universal precursor for vancosamine derivatives, was prepared by a short scheme based on diastereoselective addition of an allenyl stannane to a lactaldehyde ether, the tungsten-catalyzed alkynol cycloisomerization, and the rhodium-catalyzed C−H insertion of a carbamate nitrogen. This sequence is a prototype for a new and efficient strategy for the synthesis of 3-amino sugar derivatives. The key intermediate was elaborated to the silyl ether of N,N-dimethyl vancosamine glycal

Regioselectivity of Rhodium Nitrene Insertion. Syntheses of Protected Glycals of l-Daunosamine, d-Saccharosamine, and l-Ristosamine

The carbamate-protected glycals of naturally occurring 3,4-cis-3-amino-2,3,6-trideoxyhexoses (l-daunosamine, d-saccharosamine, and l-ristosamine) were prepared from noncarbohydrate starting materials. The short, high-yield syntheses are based on the chemoselective insertion of a rhodium nitrene in an allylic C−H bond rather than in a C−H bond that is α to an oxygen substituent

A Synthesis of l-Vancosamine Derivatives from Non-Carbohydrate Precursors by a Short Sequence Based on the Marshall, McDonald, and Du Bois Reactions

The carbamate-protected l-vancosamine glycal, viewed as a universal precursor for vancosamine derivatives, was prepared by a short scheme based on diastereoselective addition of an allenyl stannane to a lactaldehyde ether, the tungsten-catalyzed alkynol cycloisomerization, and the rhodium-catalyzed C−H insertion of a carbamate nitrogen. This sequence is a prototype for a new and efficient strategy for the synthesis of 3-amino sugar derivatives. The key intermediate was elaborated to the silyl ether of N,N-dimethyl vancosamine glycal

Malaria-Infected Mice Live until at Least Day 30 after a New Monomeric Trioxane Combined with Mefloquine Are Administered Together in a Single Low Oral Dose

In only five simple steps and 48% overall yield from the natural trioxane artemisinin, the thermally and hydrolytically stable trioxane fluoroanilide 4b has been prepared. Upon one oral dose of only 6.8 mg/kg of monomeric trioxane 4b combined with 20 mg/kg of mefloquine hydrochloride, all of the malaria-infected mice lived until at least day 30 post infection. Of the five mice in this surviving group, four (80%) were completely cured (no parasites in their blood) and one mouse had 4% blood parasitemia. Importantly, the efficacy of this ACT chemotherapy using monomeric trioxane 4b plus mefloquine hydrochloride is considerably better than the efficacy under the same conditions using the popular trioxane drug artemether plus mefloquine hydrochloride

Malaria-Infected Mice Are Cured by a Single Dose of Novel Artemisinin Derivatives

We disclose here for the first time the curative activity of a new generation of trioxane dimers, designed logically and prepared easily from the natural trioxane artemisinin in only four or five chemical steps that would be easily accomplished also on a manufacturing scale. Four of these trioxane dimers cure malaria-infected mice after only a single subcutaneous dose, and two other dimers cure after three oral doses

Biological Mechanisms of Action of Novel C-10 Non-Acetal Trioxane Dimers in Prostate Cancer Cell Lines

The mechanisms of action of three C-10 non-acetal trioxane dimers (TDs) were examined in human (LNCaP) and mouse (TRAMP-C1A and -C2H) prostate cancer cell lines. 1 (AJM3/23), 2 (GHP-TM-III-07w), and 3 (GHP-KB-06) inhibited cell growth with 3 being the most potent in C1A (GI50 = 18.0 nM), C2H (GI50 = 17.0 nM), and LNCaP (GI50 = 17.9 nM) cells. In comparison to a standard cytotoxic agent such as doxorubicin (GI50 = 45.3 nM), 3 (GI50 = 17.9 nM) inhibited LNCaP cell growth more potently. TDs induced G0/G1 cell cycle arrest in LNCaP cells and decreased cells in the S phase. These changes correlated with modulation of G1 phase cell cycle proteins including decreased cyclin D1, cyclin E, and cdk2 and increased p21waf1 and p27Kip1. TDs also promoted apoptosis in LNCaP cells with increased expression of proapoptotic bax. These results demonstrate that TDs are potentially useful agents that warrant further preclinical development for treatment of prostate cancer

Malaria-Infected Mice Are Cured by Oral Administration of New Artemisinin Derivatives

In four or five chemical steps from the 1,2,4-trioxane artemisinin, a new series of 23 trioxane dimers has been prepared. Eleven of these new trioxane dimers cure malaria-infected mice via oral dosing at 3 × 30 mg/kg. The clinically used trioxane drug sodium artesunate prolonged mouse average survival to 7.2 days with this oral dose regimen. In comparison, animals receiving no drug die typically on day 6–7 postinfection. At only 3 × 10 mg/kg oral dosing, seven dimers prolong the lifetime of malaria-infected mice to days 14–17, more than double the chemotherapeutic effect of sodium artesunate. Ten new trioxane dimers at only a single oral dose of 30 mg/kg prolong mouse average survival to days 8.7–13.7, and this effect is comparable to that of the fully synthetic trioxolane drug development candidate OZ277, which is in phase II clinical trials

Discovery of PSI-353661, a Novel Purine Nucleotide Prodrug for the Treatment of HCV Infection

Hepatitis C virus afflicts approximately 180 million people worldwide, and the development of direct acting antivirals may offer substantial benefit compared to the current standard of care. Accordingly, prodrugs of 2′-deoxy-2′-fluoro-2′-C-methylguanosine monophosphate analogues were prepared and evaluated for their anti-HCV efficacy and tolerability. These prodrugs demonstrated >1000 fold greater potency than the parent nucleoside in a cell-based replicon assay as a result of higher intracellular triphosphate levels. Further optimization led to the discovery of the clinical candidate PSI-353661, which has demonstrated strong in vitro inhibition against HCV without cytotoxicity and equipotent activity against both the wild type and the known S282T nucleoside/tide resistant replicon. PSI-353661 is currently in preclinical development for the treatment of HCV

Discovery of PSI-353661, a Novel Purine Nucleotide Prodrug for the Treatment of HCV Infection

Hepatitis C virus afflicts approximately 180 million people worldwide, and the development of direct acting antivirals may offer substantial benefit compared to the current standard of care. Accordingly, prodrugs of 2′-deoxy-2′-fluoro-2′-C-methylguanosine monophosphate analogues were prepared and evaluated for their anti-HCV efficacy and tolerability. These prodrugs demonstrated >1000 fold greater potency than the parent nucleoside in a cell-based replicon assay as a result of higher intracellular triphosphate levels. Further optimization led to the discovery of the clinical candidate PSI-353661, which has demonstrated strong in vitro inhibition against HCV without cytotoxicity and equipotent activity against both the wild type and the known S282T nucleoside/tide resistant replicon. PSI-353661 is currently in preclinical development for the treatment of HCV

Discovery of MK-1454: A Potent Cyclic Dinucleotide Stimulator of Interferon Genes Agonist for the Treatment of Cancer

Stereochemically and structurally complex cyclic dinucleotide-based stimulator of interferon genes (STING) agonists were designed and synthesized to access a previously unexplored chemical space. The assessment of biochemical affinity and cellular potency, along with computational, structural, and biophysical characterization, was applied to influence the design and optimization of novel STING agonists, resulting in the discovery of MK-1454 as a molecule with appropriate properties for clinical development. When administered intratumorally to immune-competent mice-bearing syngeneic tumors, MK-1454 exhibited robust tumor cytokine upregulation and effective antitumor activity. Tumor shrinkage in mouse models that are intrinsically resistant to single-agent therapy was further enhanced when treating the animals with MK-1454 in combination with a fully murinized antimouse PD-1 antibody, mDX400. These data support the development of STING agonists in combination with pembrolizumab (humanized anti-PD-1 antibody) for patients with tumors that are partially responsive or nonresponsive to single-agent anti-PD-1 therapy