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Synthesis and Conformational Investigation of Methyl 4a-Carba- d -arabinofuranosides

2001; American Chemical Society; Volume: 66; Issue: 26 Linguagem: Inglês

10.1021/jo010827r

1520-6904

Christopher S. Callam, Todd L. Lowary,

Polyamine Metabolism and Applications

The synthesis of carbasugar analogues of methyl α-d-arabinofuranoside and methyl β-d-arabinofuranoside (3 and 4) is reported. The route developed involves the conversion of d-mannose into a suitably protected diene (13), which is then cyclized via olefin metathesis. The resulting cyclopentene (14) is stereoselectively hydrogenated to provide an intermediate that can be used for the synthesis of both targets. Through the use of NMR spectroscopy, we have probed the ring conformation of 3 and 4, as well as the rotamer populations about the C4−C5 and C1−O1 bonds. These studies have demonstrated that there are differences in ring conformation between these carbasugars and their glycoside parents (1 and 2). However, only minor differences are seen in the rotameric equilibrium about the C4−C5 bond in 3 and 4 relative to 1 and 2. In regard to the C1−O1 bond, NOE data from 3 and 4 suggest that the favored position about this bond is similar to that in the glycosides; that is, the methyl group is anti to C2. However, confirmation of this preference through measurement of 3JC,C between the methyl group and C2 or C4a was not successful.