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Iron Carbonyl Induced Reactions of Norbornene Derivatives with Substituted Acetylenes
Author(s) -
Hayakawa Kenji,
Schmid Hans
Publication year - 1977
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.19770600708
Subject(s) - chemistry , dimethyl acetylenedicarboxylate , phenylacetylene , acetic anhydride , cyclopentanone , diphenylacetylene , medicinal chemistry , cyclopentenone , norbornadiene , organic chemistry , cyclohexenone , norbornene , pyridine , acetylene , cycloaddition , catalysis , polymer , monomer
Photochemical reactions of norbornadiene with substituted acetylenes in the presence of Fe(CO) 5 gave various products of different types, depending on the nature of the acetylene. The results are summarized in Table 1 . The cyclopentanone 1 was always formed in these reactions. In the reaction of disubstituted acetylenes such as dimethyl acetylenedicarboxylate and ethyl phenylpropiolate, the cyclopentenones 2 and 5 were formed, respectively. By contrast, propiolic esters produced the cyclohexenones 3 and 4 , in which the ester group was attached on the β carbon with respect to the keto group. Plausible mechanisms for the formation of these products are shown in Schemes 7 and 8 . The reaction of diphenylacetylene gave the cyclohexendione 7 as well as the cyclopentenone 6 . Two enedione products 8 and 9 were obtained from the reaction of phenylacetylene. Compound 9 was converted to the aromatic diacetate 13 by heating with acetic anhydride in pyridine. On irradiation in the presence of Fe(CO) 5 norbornene reacted similarly with dimethyl acetylenedicarboxylate and phenylacetylene to give the cyclopentenone 14 and the cyclohexenone 15 , respectively. Compound 15 , upon heating, isomerized to hydroquinone 16 , which on acetylation gave the diacetate 17 .