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Synthesis 1987; 1987(2): 134-137
DOI: 10.1055/s-1987-27861
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Oxokohlenstoffe und verwandte Verbindungen; 12. Mitteilung. Eine einfache Synthese von 3-Hydroxy-3-cyclobuten-1,2-dion ("Semiquadratsäure"; "Moniliformin") und dessen Umsetzung mit Aminen

Arthur H. Schmidt* , Harry Maibaum
  • *Abteilung für Organische Chemie und Biochemie, Fachhochschule Fresenius, Kappellenstraße 11-15, D-6200 Wiesbaden, West Germany
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Publikationsdatum:
12. September 2002 (online)

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Oxocarbons and Related Compounds; Part 12. A Simple and Efficient Synthesis of 3-Hydroxy-3-cyclobutene-1,2-dione ("Semisquaric Acid"; "Moniliformin") and its Reaction with Amines Starting with squaric acid (1), semisquaric acid (4) has been synthesized in a 54% overall yield. In contrast to a literature report semisquarie acid (4) reacts with ammonia (5a) and aniline (5b) in the cold to give the ammonium-semisquarates 6a and 6b, respectively, and not the corresponding semisquaric amides. Accordingly, several primary, secondary, and tertiary amines react with 4 to afford the semisquarates 6c-k. Semisquaric amide (8) has been obtained unambiguously by the catalytic hydrogenation of 3-amino-4-chloro-3-cyclobutene-1,2-dione (7).