Cationic cascade cyclizations terminated by MOM ether derivatives of B-keto esters

It has been known for some time that cationic cascade cyclizations initiated by Lewis acid mediated opening of an epoxide can be trapped by reaction with a B-keto ester. The studies reported here show that the efficiency of these cyclizations can be improved through preparation of a MOM enol ether f...

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Bibliographic Details
Published inTetrahedron letters Vol. 120
Main Authors Ulrich, Natalie C., Yu, Jose S., Wiemer, David F.
Format Journal Article
LanguageEnglish
Published OXFORD Elsevier 28.04.2023
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
Cation cascade
POTENT
MOM ether
Cyclization
Epoxide
1ST TOTAL-SYNTHESIS
BIOLOGICAL EVALUATION
ACAT INHIBITOR
Rearrangement
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Summary:It has been known for some time that cationic cascade cyclizations initiated by Lewis acid mediated opening of an epoxide can be trapped by reaction with a B-keto ester. The studies reported here show that the efficiency of these cyclizations can be improved through preparation of a MOM enol ether from the B-keto ester. Furthermore, in both geranyl and farnesyl derivatives the stereochemistry of the enol ether controls formation of the major product. In both series, the E-enol ether leads to a cyclic vinylogous carbonate incorporating the oxygen originating in the ketone in the ring system, while the Z-enol ether leads to a cyclic enone incorporating the oxygen originating in the ester carbonyl group. Upon treatment with catalytic HCl, a facile rearrangement converts the enone product to the vinylogous carbonate. Because these cyclizations faithfully extend the stereochemistry of the original epoxide into multiple stereocenters, they have the potential to afford significantly more complex structures from relatively simple starting materials. (c) 2023 Elsevier Ltd. All rights reserved.
ISSN:0040-4039
1873-3581
DOI:10.1016/j.tetlet.2023.154450