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| PAPER | Synthesis 2006: 4212-4218
DOI: 10.1055/s-2006-950359 |
© Georg Thieme Verlag Stuttgart · New York
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Trimethylene Dithioacetals of Carbohydrates, Part 6: C-C Coupling Reactions of Dilithiated N-Acetyl-d-glucosamine Trimethylene Dithioacetal Derivatives
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| Yue-Lei Chena,b, Robin Leguijta, Hartmut Redlich*a, Roland Fröhlicha |
a Organisch-Chemisches Institut der Westfälischen Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
Fax: +49(251)839772;
b NRW Graduate School of Chemistry, Corrensstraße 36, 48149 Münster, Germany
e-Mail: redlich@uni-muenster.de;
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Received
30 April 2006 |
Abstract
While 3,4;5,6-di-O-isopropylidene-N-phthaloyl-d-glucosamine propane-1,3-diyl dithioacetal (2) underwent fast β-elimination, the corresponding N-acetyl derivative 3 was easily deprotonated with butyllithium to form the dilithiated intermediate 7, which was stabilized by the α-lithium imidate and reacted well with various electrophilic reagents to yield the chain-elongated products 11a-c and 12a,b. The reaction between the intermediate 7 and an unreactive 3-ulose 13 indicates that the former has pronounced reactivity compared to its α-oxy analogue. The N-tert-butoxycarbonyl derivative 4 also reacted with electrophilic reagents to yield the C-C coupling products, but always with lower yields. Key words
d-glucosamine trimethylene dithioacetal - chiral pool - carbanion - imidate anion - chain extension
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