Carbocyclization of carbohydrates: diastereoselective synthesis of (+)-gabosine F, (-)-gabosine O, and (+)-4-epi-gabosine O.
Exploitation of silica gel/chloramine T mediated intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar-derived oximes to carbocycles furnished the first synthesis of gabosine F from l-arabinose in 12 steps with 23% overall yield, thereby confirming its absolute configuration. Similarly, efficient syntheses of gabosine O and 4-epi-gabosine O were accomplished from D-mannose in 9 and 11 steps with 41% and 38% overall yields, respectively, involving INOC, regioselective dehydration, and diastereoselective hydrogenation as the key steps.
Department of Chemistry and Center of Novel Functional Molecules, The Chinese Univeristy of Hong Kong, Shatin, Hong Kong, China. tonyshing@cuhk.edu.hk
Tony K M
TK
Shing
King H
KH
So
Wun S
WS
Kwok
D001089:Arabinose / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003512:Cyclohexanones / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D002241:Carbohydrates; D003512:Cyclohexanones; C545816:gabosine F; C545818:gabosine O; D001089:Arabinose