http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Trans.%20Metal.%20catal.%20reactions%20Chem.%20rev.%20042127.pdf

Transition-Metal-Catalyzed Reactions in Heterocyclic Synthesis

Enantioselective catalytic aziridinations and asymmetric nitrene insertions into CH bonds.

The element nitrogen is essential to life. Considerable attention is thus paid to the development of synthetic methods for its introduction into molecules. Nitrenes, long regarded as highly reactive but poorly selective species, have recently emerged as useful tools for the formation of CN bonds. Practical metal-catalyzed protocols are now available for the preparation of amines through either the aziridination of alkenes or the CH amination of alkanes. Recent results highlighted in this Minireview suggest that synthetic nitrene chemistry is maturing with a wider scope not limited to these two reactions.

Nitrene Chemistry in Organic Synthesis: Still in Its Infancy?

Therapeutic vaccines derived from carbohydrate antigen-adjuvant combinations are a promising approach for cancer immunotherapy. One of the critical limitations in this area is access to sufficient quantities of tumour-associated carbohydrate antigens and glycoconjugate adjuvants. At present, availability of the complex oligosaccharide constructs that are needed for the systematic design and evaluation of novel vaccine formulations relies on de novo chemical synthesis. The use of both state-of-the-art and emerging glycosylation technologies has led to significant advances in this field, allowing the clinical exploration of carbohydrate-based antigens in the treatment of cancer.

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Chemical glycosylation in the synthesis of glycoconjugate antitumour vaccines

1,2-Amino alcohols are high-value, versatile functional groups that are found in scores of biologically active molecules and other interesting synthetic targets such as ligands and auxiliaries. Given their prominent position within organic compounds of import, it is no surprise to note that many routes have been developed to access this motif and there are many different starting points from which a synthetic chemist might embark on a synthesis. However, one particular approach stands out from the others, and this is the direct conversion of an alkene to a vicinal amino alcohol derivative (oxyamination). Research in this field has been particularly active in recent years and many interesting new methodologies have been reported. The purpose of this review is to give the reader a tour of the methods that have emerged in the last few years so one can appreciate the myriad of different metals and reagents that can accomplish the oxyamination of alkenes. There are still many challenges to be overcome and, herein, we also outline the areas that are ripe for further development and which bode well for the future.

Recent developments in methodology for the direct oxyamination of olefins.

Amidoglycosylation via Metal-Catalyzed Internal Nitrogen Atom Delivery

Glucal 3-carbamates 1 and 7 underwent oxidative cyclization with iodobenzene diacetate or iodosobenzene in the presence of Rh2(OAc)4, providing mannosamine 2-N,3-O-oxazolidinones. With iodosobenzene, incorporation of 4-penten-1-ol provided a readily separable anomeric mixture of n-pentenyl glycosides, with the anomers exhibiting pronounced differences in reactivity as glycosyl donors. N-acylation of the sugar oxazolidinones led to α-selective glycosyl donors for the elaboration of various 2-mannosamine frameworks. Alternatively, the anomeric n-pentenyl glycosides of N-Cbz 2-mannosamine oxazolidinones were converted separately to oxazolidinone-opened derivatives 28α and 28β. These served as stereoconvergent glycosyl donors, and the α-linked products were readily advanced to a variety of N-acetylmannosamine (ManNAc) frameworks, using an intramolecular O→N acetyl transfer as the final step.

Christian M. Rojas

Papers

Amidoglycosylation via Metal-Catalyzed Internal Nitrogen Atom Delivery

α-N-acetylmannosamine (ManNAc) synthesis via rhodium(II)-catalyzed oxidative cyclization of glucal 3-carbamates

Photo amidoglycosylation of an allal azidoformate. Synthesis of beta-2-amido allopyranosides.

Protecting group and solvent control of stereo- and chemoselectivity in glucal 3-carbamate amidoglycosylation.

The Mislow–Evans Rearrangement