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.
Shing
Tony K M
TK
Department of Chemistry and Center of Novel Functional Molecules, The Chinese Univeristy of Hong Kong, Shatin, Hong Kong, China. tonyshing@cuhk.edu.hk
So
King H
KH
Kwok
Wun S
WS
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