There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Advances in the chemical synthesis of C-pyranosides/furanosides are summarized, covering the literature from 2000 to 2016. The majority of the methods take advantage of the construction of the glycosidic C—C bond. These C-glycosylation methods are categorized herein in terms of the glycosyl donor precursors, which are commonly used in O-glycoside synthesis and are easily accessible to nonspecialists. They include glycosyl halides, glycals, sugar acetates, sugar lactols, sugar lactones, 1,2-anhydro sugars, thioglycosides/sulfoxides/sulfones, selenoglycosides/telluroglycosides, methyl glycosides, and glycosyl imidates/phosphates. Mechanistically, C-glycosylation reactions can involve glycosyl electrophilic/cationic species, anionic species, radical species, or transition-metal complexes, which are discussed as subcategories under each type of sugar precursor. Moreover, intramolecular rearrangements, such as the Claisen rearrangement, Ramberg–Backlund rearrangement, and 1,2-Wittig rearrangement, which usuall...

Recent Advances in the Chemical Synthesis of C-Glycosides

Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Vinyl epoxides in organic synthesis.

ConspectusCarbon monoxide is widely acknowledged as an important gasotransmitter in the mammalian system with importance on par with that of nitric oxide. It has also been firmly established as a potential therapeutic agent with a wide range of indications including organ transplantation, cancer, bacterial infection, and inflammation-related conditions such as colitis and sepsis. One major issue in developing CO based therapeutics is its delivery in a pharmaceutically acceptable form. Currently, there are generally five forms of deliveries: inhaled CO, photosensitive CO-releasing molecules, encapsulated CO, CO dissolved in drinks, and molecules that would release CO under physiological conditions without the need for light. For over a decade, the last category only included metal-based CO releasing molecules. What had been missing were organic CO prodrugs, which release CO under physiological conditions with tunable rates and in response to various exogenous and endogenous triggers such as water, chemical...

Strategies toward Organic Carbon Monoxide Prodrugs

A prodrug strategy for the release of the gasotransmitter CO at physiological pH, based upon 3a-bromo-norborn-2-en-7-one Diels–Alder cycloadducts of 2-bromomaleimides and 2,5-dimethyl-3,4-diphenylcyclopentadienone has been developed Examples possessing protonated amine and diamine groups showed good water solubility and thermal stability Half-lives for CO-release in TRIS-sucrose buffer at pH 74 ranged from 19 to 75 min at 37 °C and 31 to 32 h at 4 °C Bioavailability in rats was demonstrated by oral gavage and oCOm-21 showed a dose dependent vasorelaxant effect in pre-contracted rat aortic rings with an EC50 of 16 ± 09 μM Increased intracellular CO levels following oCOm-21 exposure were confirmed using a CO specific fluorescent probe

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Norborn-2-en-7-ones as physiologically-triggered carbon monoxide-releasing prodrugs

The conversion of cyclopropane-fused carbohydrates into oxepines is an attractive method for accessing diverse members of the septanoside family of carbohydrate mimetics. 2-Bromooxepines are obtained through silver(I)-promoted thermal ring expansion of a d-glucal-derived gem-dihalocyclopropanated sugar. In contrast, cyclopropane ring cleavage under basic conditions leads to 2-C-branched pyranosides, not the 2-bromooxepine structures assigned in an earlier report.

Synthesis of oxepines and 2-branched pyranosides from a d-glucal-derived gem-dibromo-1,2-cyclopropanated sugar.

Investigations of the Thermal Responsiveness of 1,4,2-Oxathiazoles

Synthesis of C-furanosides from a D-glucal-derived cyclopropane through a ring-expansion/ring-contraction sequence

Addition of a carbene to a glycal is the prominent method for the synthesis of 1,2-cyclopropyl car- bohydrates. This incorporation of a cyclopropane into a carbohydrate scaffold enables divergent reactivity, with the two main classes being ring expansion and cleavage to 2- C -branched carbohydrates. A wide variety of products are obtained depending on the functionality attached to the cyclopropane (none or ester or hal- ogens) and the promoter (Lewis acid, Br o nsted acid, halophile or base) used in the reaction. This article reviews progress in the synthesis and reactions of 1,2-cyclopropyl carbohydrates since 2000 and discloses efforts by our group in the area.

Russell J. Hewitt

Papers

Norborn-2-en-7-ones as physiologically-triggered carbon monoxide-releasing prodrugs

Synthesis of oxepines and 2-branched pyranosides from a d-glucal-derived gem-dibromo-1,2-cyclopropanated sugar.

Investigations of the Thermal Responsiveness of 1,4,2-Oxathiazoles

Synthesis of C-furanosides from a D-glucal-derived cyclopropane through a ring-expansion/ring-contraction sequence

Reactions of 1,2-cyclopropyl carbohydrates