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Cyclization of ethyl ( E )/( Z )‐[2‐(1‐cyclohexen‐1‐yl)cyclohexylidene]cyanoacetate to 10‐amino‐1,2,3,4,5,6,7,8‐octahydrophenanthrene‐9‐carboxylic acid — a route to 1,2,3,4,5,6,7,8‐octahydrophenanthrene derivatives
Author(s) -
Wilamowski Jaroslaw,
Krasodomski Wojciech,
Nowak Barbara,
Sepioł Janusz J.
Publication year - 1995
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.1995199508216
Subject(s) - chemistry , decarboxylation , carboxylic acid , ethyl cyanoacetate , sulfuric acid , ethyl ester , organic chemistry , medicinal chemistry , cyclohexane , amine gas treating , catalysis , malononitrile
Cyclization of ethyl ( E )/( Z )‐[2‐(1‐cyclohexen‐1‐yl)cyclohexylidene]cyanoacetate ( 2 ) in cold concentrated sulfuric acid affords 10‐amino‐1,2,3,4,5,6,7,8‐octahydrophenanthrene‐9‐carboxylic acid ( 4 ) and 3,5,6,7,8,8a‐hexahydro‐3‐oxospiro‐[1 H ‐2‐benzopyran‐1,1′‐cyclohexane]‐4‐carbonitrile ( 5 ). The o ‐amino acid 4 is employed in the synthesis of several 1,2,3,4,5,6,7,8‐octahydrophenanthrene derivatives: the carboxylic acid 6 , o ‐hydroxy carboxylic acid 7 , and the amine 8 . The lactone 5 undergoes decarboxylation on heating yielding a mixture of unsaturated nitriles 9 and 10 which are cyclized to the amine 8 .