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Free-radical mediated synthesis of enantiomerically pure, highly functionalized inositols from carbohydrates
We report the synthesis, free-radical cyclization of precursors 1,2,7-trideoxy-7-iodo-3,4:5,6-di- O-isopropylidene- d- gluco-hept-1-enitol ( 1), methyl 7- O-acetyl-6- O-benzyl-8-bromo-2,3,8-trideoxy-4,5- O-isopropylidene- d- gluco-oct-2-enonate ( 2) and 5- O-acetyl-4- O-benzyl-6-bromo-6-deoxy-2,3- O...
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Published in: | Carbohydrate research 2001-06, Vol.332 (4), p.341-349 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | We report the synthesis, free-radical cyclization of precursors 1,2,7-trideoxy-7-iodo-3,4:5,6-di-
O-isopropylidene-
d-
gluco-hept-1-enitol (
1), methyl 7-
O-acetyl-6-
O-benzyl-8-bromo-2,3,8-trideoxy-4,5-
O-isopropylidene-
d-
gluco-oct-2-enonate (
2) and 5-
O-acetyl-4-
O-benzyl-6-bromo-6-deoxy-2,3-
O-isopropylidene-
d-glucose-
O-benzyloxime (
3), readily prepared from
d-glucose, and some selected transformations of the carbocycles obtained from these intermediates. In compound
1 we have installed a terminal double bond and an iodide as radical acceptor and leaving group, respectively. Compounds
2 and
3 are ε-bromo aldehydes substituted with α,β-unsaturated ester and oxime ether functions as radical traps, respectively. The tributyltin hydride mediated ring closure of these radical precursors have afforded a series of interesting, diverse and highly functionalized carbocycles which can be considered useful building blocks for the synthesis of branched-chain cyclitols, aminocyclitols and aminoconduritols. In these processes, a good chemical yield and high stereoselectivity has been found in the newly formed stereocenters. Particularly interesting has been the finding that the stereochemical outcome of the free-radical cyclization is independent of the ratio of isomers (
E or
Z) in oxime ether
3. These results show the power and the state of art of this strategy for the stereocontrolled synthesis of enantiomerically pure inositols from carbohydrates.
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ISSN: | 0008-6215 1873-426X |
DOI: | 10.1016/S0008-6215(01)00116-1 |