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Face Selectivity of the Diels ‐ Alder Reaction of Hexadienone Moieties Grafted onto the Bicyclo[2.2.2]octene Skeleton and Perturbed by a Remote Tricarbonylbutadieneiron Group
Author(s) -
Tagliaferri Enrico,
Hänisch Ulrich,
Roulet Raymond,
Vogel Pierre,
Schenk Kurt J.
Publication year - 1985
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19850680529
Subject(s) - chemistry , dimethyl acetylenedicarboxylate , cycloaddition , methyl vinyl ketone , ketone , bicyclic molecule , selectivity , stereoselectivity , adduct , stereochemistry , medicinal chemistry , derivative (finance) , methyl ketone , organic chemistry , catalysis , financial economics , economics
Selective oxidations of bis(tricarbonyliron) complexes of methyl (3,7,8‐trimethylidenebicyclo[2.2.2]oct‐5‐en‐2‐ylidene)methyl ketones 15 – 17 afforded selectively the tricarbonyl {(1 RS ,4 SR ,7 SR ,8 RS )‐ C ,7,8, C ‐η‐[methyl (3,7,8‐trimethylidenebicyclo[2.2.2]oct‐5‐en‐(2 Z )‐2‐ylidene)methyl ketone]}iron ( 12 ), the corresponding (2 E )‐derivative 13 and the tricarbonyl{(1 RS ,2 RS ,3 SR ,4 SR )‐ C ,2,3, C ‐η‐[methyl (3,7,8‐trimethylidenebicyclo[2.2.2]oct‐5‐en‐(2 Z )‐2‐ylidene)methyl ketone]}iron ( 18 ). The stereoselectivity of the Diels ‐ Alder reactions of the uncomplexed ( Z )‐ and ( E )‐hexadienone 12 and 13 , respectively, was established. The face of the diene syn with respect to the C(5), C(6) etheno bridge was preferred for the cycloadditions of N ‐phenyltriazolinedione (NPTAD). In contrast, the reactions of dimethyl acetylenedicarboxylate (DMAD) and methyl propynoate showed a slight preference for addtion to the face of the hexadienones anti with respect to the etheno bridges of 12 and 13 . The crystal structure of the adduct 25 resulting from the cycloaddition of NPTAD to 12 is reported.