Enantioselective synthesis of (−)-meroquinene through tandem Michael reaction methodology
An enantioselective approach to the synthesis of non natural (−)-meroquinene 1 based on sequential inter- and intramolecular Michael reaction between (L)-menthyl N-benzyl-5-amino-2E-pentenoate 3 and 1-acetyloxy-4-methoxymethyloxy-2-nitrobutane 10b, acting as surrogate of 2-nitro-1,3-butadiene 4, is...
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Published in | Tetrahedron Vol. 50; no. 8; pp. 2583 - 2590 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
OXFORD
Elsevier Ltd
21.02.1994
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | An enantioselective approach to the synthesis of non natural (−)-meroquinene
1 based on sequential inter- and intramolecular Michael reaction between (L)-menthyl N-benzyl-5-amino-2E-pentenoate
3 and 1-acetyloxy-4-methoxymethyloxy-2-nitrobutane
10b, acting as surrogate of 2-nitro-1,3-butadiene
4, is described. The heterocyclization process led to the formation of the piperidine ring system
12, obtained as an unseparable 80:20 mixture of diastereomers at the newly created chiral centres at C-3 and C-4, which became easily separable by column chromatography after transformation of the nitrogen protective benzyl group into the corresponding carbamates
14 and
15. Both compounds, after elaboration of the chain geminal to the nitro group into a vinyl appendage. underwent regio- and stereo-selective removal of the nitro group by palladium-catalyzed displacement with hydride generated by formate to give the precursor
19, easily converted by treatment with hydrochloric acid to
1, isolated as hydrochloride.
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ISSN: | 0040-4020 1464-5416 |
DOI: | 10.1016/S0040-4020(01)86974-X |