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4,5‐Dibenzyloxybenzyne as a synthon for diels‐alder reactions. The synthesis of 6,7‐dihydroxy‐1,4‐ethano‐1,2,3,4‐tetrahydroisoquinolines as rigid analogs of adrenergic agents. Assignment of proton and carbon‐13 NMR parameters using homonuclear and heteronuclear two‐dimensional chemical shift correlation NMR spectroscopy
Author(s) -
Muellner Frank W.,
AbdelSayed Ashraf N.,
Bauer Ludwig
Publication year - 1985
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570220426
Subject(s) - chemistry , heteronuclear molecule , homonuclear molecule , synthon , chemical shift , stereochemistry , nuclear magnetic resonance spectroscopy , cycloaddition , medicinal chemistry , organic chemistry , molecule , catalysis
Abstract The synthesis of several rigid analogs of catecholamine type of adrenergic agents is reported. Their synthesis began with a Diels‐Alder cycloaddition of 4,5‐dibenzyloxybenzyne (generated from 4,5‐dibenzyloxyan‐thranilic acid) to 1‐(2‐ trans ‐phenylvinyl)‐2‐pyridone and 1‐benzyl‐3‐benzyloxy‐2‐pyridone. The unsaturated amides so produced were reduced first with hydrogen and palladium and then with lithium aluminum hydride to provide 6,7‐dihydroxy‐1,4‐ethano‐1,2,3,4‐tetrahydroisoquinolines. Homonuclear and heteronuclear two‐dimensional chemical shift correlation nmr spectroscopy confirmed the structure of the bridged tetra‐hydroisoquinolines and led to the unambiguous assignment of the 1 H and 13 C nmr chemical shifts of key compounds.