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Synthesis of Functionalized Cycloprop[ f ]indenes via the Carbene Addition Route
Author(s) -
Müller Paul,
Miao Zhongshan
Publication year - 1994
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.19940770729
Subject(s) - chemistry , indene , dichlorocarbene , aromatization , cycloaddition , medicinal chemistry , diethyl azodicarboxylate , malonate , diethyl malonate , curtius rearrangement , cyclopentene , adduct , stereochemistry , organic chemistry , triphenylphosphine , catalysis
The synthesis of 4,5‐dihydro‐1 H ,3 H ‐cycloprop[ f ]inden‐4‐ol ( 1 ) and diethyl 4,5‐dihydro‐1 H ,3 H ‐cycloprop[ f ]‐indene‐4,4‐dicarboxylate ( 26 ) starting from diene 4 is described. The cyclopentene ring is constructed by condensation of diethyl malonate to the dibromide 21 . The key‐step in the synthesis of 1 consists in a twofold Curtius degradation of 22 , with subsequent reduction of the carbonyl group and aromatization. The skeleton of the isomer 31 is synthesized via cycloaddition of butadiene to cyclopent‐4‐ene‐1,3‐dione ( 7 ) and addition of dichlorocarbene to the adduct 27 after ketalisation. The attempted synthesis of dihydrocycloprop[ f ]indene ( 2 ) by base‐induced elimination of several appropriately substituted precursors failed.