Introduction 3605 2. Synthesis of Perlin Aldehydes 3606 2.1. Mercurial Approach 3606 2.2. Nonmercurial Approach 3606 3. Mechanism for the Formation of Perlin Aldehydes from 3,4,6-Tri-O-acetyl-D-glucal 3607 4. Applications of Perlin Aldehydes 3607 4.1. Synthesis of Natural Products and Related Compounds 3607 4.2. Synthesis of Nucleosides 3621 4.3. Cycloaddition Reactions3623 4.3.1. Intramolecular Pauson-Khand Cycloaddition 3623 4.3.2. Diels−Alder Reaction 3623 4.3.3. Annulation Reaction 3624 4.4. Stereoselective Synthesis of Tetrahydroquinolines, 1,5-Benzodiazepines and N-Aryltetrahydropyridines 3624 4.5. Stereoselective Synthesis of C-(Alkynyl)-, C-(Allyl)-, and C-(Cyano)-pseudoglycals 3625 4.6. Synthesis of 2,3-Epoxy Alcohols, Trisubstituted Tetrahydrofurans and Their Derivatives 3626 4.7. Synthesis of Optically Pure β-Lactams 3626 4.8. Aldol Addition Reaction 3626 4.9. Morita-Baylis-Hillman (MBH) Chemistry 3627 4.10.

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A new series of monosaccharide-based glycolipids devoid of phosphate groups and with two lipid chains were rationally designed by varying the lipid chain lengths and saccharide structure of a α-GalCer-derived lead compound (CCL-34) that is a potent TLR4 agonist. The NF-κB activity of a 60-membered galactosyl serine-based synthetic library containing compounds with various lipid chain lengths was measured in a HEK293 cell line that stably expressed human TLR4, MD2, and CD14 (293-hTLR4/MD2-CD14). The results showed that the optimal carbon chain lengths for the lipid amine and fatty acid to activate TLR4 were 10-11 and 12, respectively. Evaluation of a 20-membered synthetic glycosyl serine-based lipid library containing compounds with various saccharide moieties and fixed lipid chain lengths revealed that the galactose moiety in CCL-34 could be replaced by glucose without loss of activity (CCL-34-S3 and CCL-34-S16). Changing the orientation of the anomeric glycosidic bond of CCL-34 resulted in a complete loss of activity (β-CCL34). Surprisingly, a change in configuration of the anomeric glycosidic bond in a glucosyl glycolipid is tolerable (CCL-34-S14). Another noteworthy observation is that the activity of a l-fucosyl derived glycolipid (CCL-34-S13) was comparable to that of CCL-34. In sum, this study determines the structural features that are crucial for an optimal TLR4-stimulating activity. It also provides several molecules with immunostimulating potential.

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A new and highly efficient methodology for the construction of synthetically important highly O-functionalized enantiopure 2,3,4-trisubstituted tetrahydrofurans with three contiguous stereocenters is reported.