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2005
Nucleic acids
U 0700
A Pauson—Khand Approach to New Carbocyclic Nucleoside Analogues. —
dienynes of type (I) are used as substrates in the Pauson—Khand reaction to
33- 245 Various
give bicyclic cyclopentenones with high diastereoselectivities. These products are
valuable building blocks for title nucleoside analogues, exemplified by compounds
(VII) and (XIII). In the case of (VII), a regio- and diastereoselective nucleobase introduction is achieved by Pd(0)-catalyzed allylic substitution. In contrast, two subsequent
Mitsunobu reactions are needed to achieve a stereocontrolled nucleobase introduction
to give finally compound (XIII). Pauson—Khand products (IIIa) and (IIIb) are obtained
in enantiomerically pure form through a highly efficient kinetic resolution by means of
asymmetric oxazaborolidine-catalyzed borane reduction. — (LANVER, A.;
SCHMALZ*, H.-G.; Eur. J. Org. Chem. 2005, 7, 1444-1458; Inst. Org. Chem., Univ.
Koeln, D-50939 Koeln, Germany; Eng.) — Klein
2005
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