A versatile route to enantiopure 3,3-disubstituted oxindoles and 3a-substituted pyrrolidinoindolines is described in which diastereoselective dialkylation of enantiopure ditriflate 10 with oxindole enolates is the central step. These reactions are rare examples of alkylations of prostereogenic enolates with chiral sp(3) electrophiles that proceed with high facial selectivity (10-20:1). The scope of this method is explored, and a model to rationalize the sense of stereoselection is advanced. This dialkylation chemistry was used to synthesize (-)-phenserine on a multigram scale in six steps and 43% overall yield from 5-methoxy-1,3-dimethyloxindole (27) and to complete a short formal total synthesis of (-)-physostigmine (2).

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While the treatment of herpes simplex virus type 2 (HSV-2) infections with acyclovir (ACV) and similar nucleoside analogs was one of the first success stories in antiviral chemotherapy, substantial unmet medical needs remain for diseases caused by herpesviruses. The increasing immunocompromised population, particularly AIDS patients and patients with transplants, has driven the need for improved antiviral agents to treat diseases caused by herpesviruses (6, 12). Although human cytomegalovirus (HCMV) is generally benign in the immunocompetent host, reactivation of HCMV is associated with significant morbidity and mortality in immunocompromised individuals. Active HCMV infection is associated with clinical syndromes such as pneumonia, retinitis, hepatitis, gastrointestinal disease, and congenital birth defects (2, 5, 7, 10, 12). The other human herpesviruses such as HSV-1, HSV-2, and varicella-zoster virus (VZV) also occur at a greater incidence and severity in the immunocompromised population (6, 17). Resistance to the currently available nucleoside analog antivirals does occur in this population, compounding the difficulty in treating these viral infections (11,18). Ganciclovir (GCV), foscarnet, cidofovir, and formivirsen, the only drugs approved for treatment of HCMV infections, are less than ideal agents due to their significant toxicity, modest efficacy, and poor oral bioavailability (3, 17). Clearly, less-toxic, orally available alternatives are needed for treating herpesvirus infections in immunocompromised patients. In order to address this unmet medical need, we initiated a program to identify novel nonnucleoside inhibitors of herpesvirus DNA polymerases through broad screening of our compound collection.Polymerases are classified according to their sequences and functional homologies. All herpesvirus polymerases belong to the family B DNA polymerases (1). Several eukaryotic polymerases, including human ␣ and ␦ polymerases, also belong to this family of DNA polymerases with human ␦ polymerase sharing the highest degree of homology with the herpesvirus polymerases (1). These family B DNA polymerases share six to seven highly conserved domains labeled I through VII, in decreasing order of conservation (8,9). In addition to these family B conserved domains, herpesvirus DNA polymerases share an additional conserved domain referred to as the A or ␦ domain (4). Hence, broad inhibition of herpesvirus polymerases may be possible if compounds target conserved domains shared among the herpesvirus polymerases but not shared among other eukaryotic polymerases such as human ␣ and ␦ DNA polymerases. Approximately 80,000 compounds were screened for inhibition of the HCMV polymerase. Since the goal was to identify DNA polymerase inhibitors that demonstrate broad activities against the herpesviruses with no activity against host cell DNA polymerases, active compounds were further evaluated for inhibition of the HSV-1 and VZV polymerases and human polymerases ␣, ␦, and ␥.One of the most promising leads from high-throughput

The lasonolides are novel polyketides that have displayed remarkable biological activity in vitro against a variety of cancer cell lines. Herein we describe our first generation approach to the formal synthesis of lasonolide A. The key findings from these studies ultimately allowed us to go on and complete a total synthesis of lasonolide A. The convergent approach unites two highly complex fragments utilizing a Ru-catalyzed alkene-alkyne coupling. This type of coupling typically generates branched products, however through a detailed investigation we are now able to demonstrate that subtle structural changes to the substrates can alter the selectivity to favor the formation of the linear product. The synthesis of the fragments features a number of atom economical transformations which are highlighted by the discovery of an engineered enzyme to perform a dynamic kinetic reduction of a β-ketoester to establish the absolute stereochemistry of the southern tetrahydropyran ring with high levels of enantioselectivity.

Lasonolide A is a novel polyketide displaying potent anticancer activity across a broad range of cancer cell lines. Here, an enantioselective convergent total synthesis of the (–)-lasonolide A in 16 longest linear and 34 total steps is described. This approach significantly reduces the step count compared to other known syntheses. The synthetic strategy utilizes alkyne-bearing substrates as core building blocks and is highlighted by stitching together two similarly complex halves via a key Ru-catalyzed alkene-alkyne coupling and macrolactonization.