Herein we report a novel strategy for the design and construction of natural and natural productlike libraries based on the principle of priVileged structures, a term originally introduced to describe structural motifs capable of interacting with a variety of unrelated molecular targets. The identification of such privileged structures in natural products is discussed, and subsequently the 2,2-dimethylbenzopyran moiety is selected as an inaugural template for the construction of natural product-like libraries via this strategy. Initially, a novel solid-phase synthesis of the benzopyran motif is developed employing a unique cycloloading strategy that relies on the use of a new, polystyrene-based selenenyl bromide resin. Once the loading, elaboration, and cleavage of these benzopyrans was established, this new solid-phase method was then thoroughly validated through the construction of six focused combinatorial libraries designed around natural and designed molecules of recent biological interest.

Having developed a reliable and versatile solid-phase strategy for the split-and-pool synthesis of naturally occurring and designed derivatives of the benzopyran template (see preceding paper), we now report the construction of a 10 000-membered natural product-like compound library for chemical biology studies. Concomitantly, we report an early application of the IRORI NanoKan optical encoding system for the high throughput nonchemical tagging and sorting of library members during split-and-pool synthesis. The overall synthetic strategy for library construction is discussed and the individual reaction pathways are examined in the context of specific library members, illustrating reaction conditions as well as yields and purities. The issues of building block selection and quality control of library members are also addressed and, finally, potential applications of the library to chemical biology are discussed.

The field of carbohydrate chemistry has occupied the minds and hearts of many scientists for over a hundred years and, as we enter the twenty-first century, it continues to be both vigorous and challenging. Among the most exciting aspects of organic chemistry in the last few decades has been the interplay between the specialized subdisciplines of carbohydrate chemistry and total synthesis, each enabling and advancing the other in new directions and towards greater heights. In this review article we highlight our own adventures at the interface of these disciplines, which were driven for the most part by objectives in chemical synthesis and chemical biology. Specifically, we describe our interests and efforts to utilize carbohydrates as starting materials for total synthesis, to invent and develop new synthetic technologies for carbohydrate synthesis, to construct complex oligosaccharides in solution or on solid support, and to utilize carbohydrate templates as scaffolds for peptide mimetics and for molecular diversity construction. Finally, applications of the developed synthetic strategies and enabling technologies towards the solution of biologically significant problems are discussed.

As described in the preceding two papers, our interest in the construction of natural and natural product-like libraries for chemical biology studies led to the development of a new solid-phase cycloloading strategy for the construction of substituted benzopyrans. Herein, we report a parallel solution-phase method that facilitates the enhancement of both the size and diversity of these non-oligomeric benzopyran libraries using the “libraries from libraries” principle. We examine the rationale behind the use of this tandem strategy to construct discrete small molecule libraries, and describe the development of a polymer-assisted solution-phase (PASP) methodology necessary to effect the required transformations. Once developed, this chemistry is applied to two demonstration libraries.

The fine‐tuning of the protecting groups and the glycosidation conditions were the key to the successful coupling of the carbohydrate units and vancomycin aglycon in the last steps of the total synthesis of vancomycin 1. The aglycon was converted into a suitably protected acceptor and the sugar donors were sequentially attached. Removal of all the protecting groups gave synthetic vancomycin that was indentical to the natural product (1H and 13C NMR, HPLC).

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Neonatal exposure to infectious agents may result in long-term neurological disability, and is particularly associated with the subsequent development of motor and cognitive disturbances. Our previous studies have shown that treatment with alpha-phenyl-n-tert-butyl-nitrone (PBN) following exposure to lipopolysaccharide (LPS) reduces LPS-induced brain injury in the neonatal rat. To examine whether PBN has long-lasting protective effects and ameliorates LPS-induced motor and cognitive dysfunction, PBN (100 mg/kg) was administered intraperitoneally 5 min after an LPS (1 mg/kg) intracerebral injection in postnatal day 5 (P5) Sprague-Dawley rat pups. Neurobehavioral tests were carried out from P3 to P21, and brain injury was examined at 24 h and 16 days after LPS injection. Neonatal LPS exposure resulted in hyperactivity from P13 to P17 in the open field task as compared with the control rat. Neurobehavioral deficits that were still observable at P21 included dysfunction in the beam-walking and pole tests, learning and memory deficits in the passive avoidance task, and less anxiety-like response in the elevated plus-maze task. These behavioral findings were matched by LPS-induced axonal injury in the CA1 region of the middle dorsal hippocampus (HP), reduction in the size of the HP and the number of neurons in the CA1 region of the middle dorsal HP, and loss of tyrosine hydroxylase immunoreactivity in neurons in the substantia nigra and ventral tegmental areas. Treatment with PBN provided long-lasting protection against the LPS-induced axonal injury and neuronal loss, and improved the associated neurological dysfunctions in juvenile rats.

The total synthesis of vancomycin (1, Figure 1) is described. The successful plan for this synthesis involves sequential and stereoselective coupling of vancomycin aglycon acceptor 6 and glycosyl donors, trichloroacetimidate 50 and glycosyl fluoride 27 (Scheme 8). Acceptor 6 was synthesized from vancomycin aglycon (2) (Scheme 1), which was derived both by total synthesis and by semisynthesis from vancomycin itself (1) (Scheme 2). The vancosamine derivative 27 was obtained by total synthesis (Scheme 3) while the glycosyl derivative 50 was prepared from glucal (46) (Scheme 6).A number of glycosidation model studies, carried out in order to establish the final route to vancomycin (1), are also described and so are a number of failed attempts to secure the target molecule (1).