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Synthesen von Moniliformin, einem Mycotoxin mit Cyclobutendion‐Struktur
Author(s) -
Belluš Daniel,
Fischer Hanspeter,
Greuter Hans,
Martin Pierre
Publication year - 1978
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.19780610526
Subject(s) - chemistry , cyclobutanes , ketene , cyclobutene , stereochemistry , dimer , acetal , hydrolysis , cycloaddition , organic chemistry , catalysis , ring (chemistry)
Syntheses of Moniliformin, a Mycotoxine with a Cyclobutenedione Structure Six different routes to 3‐hydroxy‐3‐cyclobutene‐1, 2‐dione ( 4 ), the free acid of the mycotoxine Moniliformin (=alkali salt of 4 ) are described. A common feature of all pathways is the synthesis of cyclobutanes having the oxidation level 6 . Moniliformin precursors which are easily transformed to 4 by acid catalysed hydrolysis include [2+2]‐cycloadducts of ketene with tetraalkoxy‐olefins, 3,4,4‐trialkoxycyclobutenes, derivatives of polyfluorinated cyclobutenes, the brominated [2+2]‐cycloadduct of ethyl vinyl ether and dichloroketene, tetrabromocyclobutanone, [2+2]‐photocycloadducts of dichlorovinylenecarbonate with dichloroethylenes, and the dimer of chloroketene. The most convenient synthesis via the [2+2]‐cycloadduct of tetraethoxyethylene and ketene ( 14b ) is reported in detail and produces 4 in four simple steps in 57% overall yield. In addition, two new syntheses of squaric acid ( 56 ) are described.