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Synthesis of Scopin Acetate and 6,7‐Didehydrohyoscyamin. Intramolecular Phenylsulfenylation of a Nonactivated Methylene Group of Ethyl N ‐Demethyl‐3‐ O ‐(phenylthio)tropine‐ N ‐carboxylate
Author(s) -
Petrović Goran B.,
Saičić Radomir N.,
Čeković Živorad M.
Publication year - 2003
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.200390258
Subject(s) - chemistry , methylene , carboxylate , ethyl acetate , olefin fiber , intramolecular force , stereochemistry , ethyl acrylate , michael reaction , medicinal chemistry , alkylation , acrylate , organic chemistry , catalysis , polymer , monomer
The synthesis of scopin acetate ( 6b ) and 6,7‐didehydrohyoscyamine ( 17 ) was achieved by using tropine ( 5 ) as the starting compound. Formal (phenylthio)‐radical transfer to the nonactivated 6‐position of ethyl N ‐demethyl‐3‐ O ‐(phenylthio)tropine‐ N ‐carboxylate ( 9 ) by irradiation in the presence of hexabutyldistannane is a key step of this synthetic approach, involving ethyl 6,7‐didehydro‐ N ‐demethyltropine‐ N ‐carboxylate ( 15 ) as a synthetic intermediate ( Schemes 3 and 5 ). The reaction of 9 with tributylstannane in the presence of ethyl acrylate, as a radicophilic olefin, involves Michael ‐type alkylation at C(6) of the tropine skeleton affording ethyl N ‐demethyl‐ N ‐(ethoxycarbonyl)tropine‐6‐propanoate ( 18 ) ( Scheme 6 ).