Alpha-N-acetylmannosamine (ManNAc) synthesis via rhodium(II)-catalyzed oxidative cyclization of glucal 3-carbamates.
[reaction: see text] 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 alpha-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 28alpha and 28beta. These served as stereoconvergent glycosyl donors, and the alpha-linked products were readily advanced to a variety of N-acetylmannosamine (ManNAc) frameworks, using an intramolecular O-->N acetyl transfer as the final step.
Bodner
Rena
R
Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, USA.
Marcellino
Bridget K
BK
Severino
Alexandra
A
Smenton
Abigail L
AL
Rojas
Christian M
CM
D002125:Calcium Gluconate / Q000031:analogs & derivatives* / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006595:Hexosamines / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D012238:Rhodium / Q000737:chemistry*
D002219:Carbamates; D006595:Hexosamines; D012238:Rhodium; D002125:Calcium Gluconate; C002022:N-acetylmannosamine