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Planar Chirality: Cycloaddition and Transannular Reactions of Optically Active Azoninones that Contain ( E )‐Olefins
Author(s) -
Sudau Alexander,
Münch Winfried,
Bats Jan W.,
Nubbemeyer Udo
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010202)7:3<611::aid-chem611>3.0.co;2-9
Subject(s) - stereocenter , chemistry , epoxide , epimer , double bond , stereochemistry , chirality (physics) , cycloaddition , optically active , ring (chemistry) , planar chirality , enantioselective synthesis , polymer chemistry , organic chemistry , catalysis , physics , nambu–jona lasinio model , quantum mechanics , quark , chiral symmetry breaking
Unsaturated nine‐membered ring lactams that contain ( E )‐olefins within the ring are characterized by planar chiral properties. Thus, selective conversions of the double bond allowed a complete transfer of the planar chiral information into new stereogenic centers. The basis of the transformations was the high activation barrier that prevented efficient flipping of the double bond at room temperature (epimerization pR ⇔ pS ) with respect to the ring. Cycloadditions led diastereoselectively to cyclopropano, epimino, epoxy, and dihydroxy azonanones under mild conditions with moderately high yields. The epoxy azonanones were subjected to regio‐ and diastereoselective transannular epoxide opening/ring contraction sequences to give hydroxy indolizidinones. The regiochemical and stereochemical outcome strongly depends on the configuration of the oxirane and the chiral information of the lactam unit. The so‐formed optically active bicycles with defined substitution patterns should serve as versatile building blocks in alkaloid synthesis.