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Synthesis and Chemistry of Endoperoxides Derived from 3,4‐Dihydroazulen‐1(2 H )‐one: An Entry to Cyclopentane‐Anellated Tropone Derivatives
Author(s) -
Çelik Murat,
Akbulut Nihat,
Balci Metin
Publication year - 2000
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 - 10.1002/1522-2675(20001220)83:12<3131::aid-hlca3131>3.0.co;2-6
Subject(s) - chemistry , tropone , thiourea , cyclopentane , tetraphenylporphyrin , peroxide , catalysis , reagent , medicinal chemistry , ketone , yield (engineering) , bicyclic molecule , organic chemistry , photochemistry , porphyrin , materials science , metallurgy
Reduction of trienone 1 and subsequent treatment with acid in MeOH furnished 1‐methoxy‐1,2,3,4‐tetrahydroazulene ( 13 ). Photo‐oxygenation of 13 provided the two bicyclic endoperoxides 14 and 15 . Pyrolysis of 14 and 15 gave the corresponding bis‐epoxides 17 and 18 , which have been synthesized also upon treatment with a catalytic amount of CoTPP (TPP=tetraphenylporphyrin). That an unusual endoperoxide‐endoperoxide rearrangement has not been observed strongly supports the assumption that the carbonyl group in 2 – 4 is responsible for this unprecedented endoperoxide‐endoperoxide rearrangement. Treatment of the endoperoxides 14 and 15 with a catalytic amount of Et 3 N at 0° provided the azulenones 22 and 23 in high yield. Attempted cleavage of the O−O peroxide linkage in 14 and 15 with thiourea resulted, contrary to our expectation, in the formation of 22 and 23 . That thiourea acts as a base instead of a reducing reagent has been observed for the first time in peroxide chemistry.