From molecules to crystal engineering: supramolecular isomerism and polymorphism in network solids.

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

The direct functionalization of C-H bonds in organic compounds has recently emerged as a powerful and ideal method for the formation of carbon-carbon and carbon-heteroatom bonds. This Review provides an overview of C-H bond functionalization strategies for the rapid synthesis of biologically active compounds such as natural products and pharmaceutical targets.

C-H bond functionalization: emerging synthetic tools for natural products and pharmaceuticals

The 3,3'-pyrrolidinyl-spirooxindole unit is a privileged heterocyclic motif that forms the core of a large family of alkaloid natural products with strong bioactivity profiles and interesting structural properties. Significant recent advances in the synthesis of this fused heterocyclic system have led to intense interest in the development of related compounds as potential medicinal agents or biological probes.

Pyrrolidinyl-spirooxindole natural products as inspirations for the development of potential therapeutic agents.

The design and implementation of cascade reactions is a challenging facet of organic chemistry, yet one that can impart striking novelty, elegance, and efficiency to synthetic strategies. The application of cascade reactions to natural products synthesis represents a particularly demanding task, but the results can be both stunning and instructive. This Review highlights selected examples of cascade reactions in total synthesis, with particular emphasis on recent applications therein. The examples discussed herein illustrate the power of these processes in the construction of complex molecules and underscore their future potential in chemical synthesis.

Cascade reactions in total synthesis.

DNA Cross-Linking Agents as Antitumor Drugs.

Studies from our laboratories on the paraherquamide, brevianamide, and asperparaline families of natural products are reviewed. It has been proposed that the unique core ring system that is common to this family of compounds arises by a biological intramolecular Diels-Alder cycloaddition reaction. Key biosynthetic studies are described, along with classical synthetic approaches as well as those inspired by Nature for the synthesis of these interesting molecules.

Paraherquamides, brevianamides, and asperparalines: laboratory synthesis and biosynthesis. An interim report.

Nature's repertoire of biosynthetic transformations has recently been recognized to include the Diels-Alder cycloaddition reaction. Evidence now exists that there are enzymes that mediate the Diels-Alder reaction in secondary metabolic biosynthetic pathways. 2002 marked the 100th anniversary of Alder's birth and 75 years since the discovery of the Diels-Alder reaction. It would appear that living systems discovered and made use of this ubiquitously useful ring-forming reaction eons ago for the construction of complex natural products. In this Review an overview is given of all of the known classes of natural products (polyketides, isoprenoids, phenylpropanoids, alkaloids) that have been speculated to arise by a biological Diels-Alder reaction.

Chemistry and Biology of Biosynthetic Diels–Alder Reactions

The Asymmetric Total Synthesis of (+)- and (−)-Spirotryprostatin B

Background Many visits to emergency departments are for minor medical problems, and these visits are criticized as being expensive and economically inefficient. This study examines the marginal costs (the extra costs for an additional visit) of emergency department visits. Methods Monthly data on the costs of hospital and physicians' services from 1991 through 1993 were obtained from a sample of six community hospitals in Michigan. The data were analyzed with ordinary least-squares regression techniques to determine the ratio of marginal to average costs. Average and marginal costs were then determined for 24,010 visits during 12 randomly selected weeks in 1993. A visit by an individual patient was the unit of analysis, and visits were classified as nonurgent, semiurgent, or urgent according to explicit criteria. Costs and charges were determined for all visits and were classified according to the degree of urgency. Results For all emergency department visits, the average charge was $383, the average cost...

Robert M. Williams

Papers

DNA Cross-Linking Agents as Antitumor Drugs.

Paraherquamides, brevianamides, and asperparalines: laboratory synthesis and biosynthesis. An interim report.

Chemistry and Biology of Biosynthetic Diels–Alder Reactions

The Asymmetric Total Synthesis of (+)- and (−)-Spirotryprostatin B

The costs of visits to emergency departments.