Oxokohlenstoffe und verwandte Verbindungen; 14. Mitteilung.<sup>1</sup>Chemie der Semiquadratsäure: Reaktive Semiquadratsäure-Abkömmlinge und deren Umsetzung mit<i>N</i>-Nucleophilen
作者:Arthur H. Schmidt、Michael Debo、Bernhard Wehner
DOI:10.1055/s-1990-26842
日期:——
Oxocarbons and Related Compounds; Part 14. The Chemistry of Semisquaric Acid: Highly Reactive Semisquaric Acid Derivatives and Their Reactions with N-Nucleophiles Starting from semisquaric acid (1), the semisquaric esters 6a-d and semisquaric chloride (7) were prepared. Reaction of 6c or 7 with amines as well as the method of mixed anhydrides, starting from 1, afforded the semisquaric amides 10a-n (Methods A, B, C, respectively). The semisquaric amides 10g,h,i were also obtained by the reaction of semisquaric chloride (7) with the trimethylsilylamines 11a-c (Method D); 10h was furthermore prepared by the DCC-method (Method E). The reaction of butyl squarate (6c) with hydrazines and N-alkylhydroxylamines afforded the semisquaric hydrazides 13a-d and the semisquaric hydroxylamides 15a-c, respectively.
Oxokohlenstoffe und verwandte Verbindungen; 15. Mitteilung.<sup>1</sup>Meerwein-Arylierung von Semiquadratsäure und Semiquadratsäureamiden. Eine allgemeine Darstellungsmethode von 3-Aryl-4-hydroxy- und 3-Amino-4-aryl-3-cyclobuten-1,2-dionen
作者:Arthur H. Schmidt、Günter Schmitt、Heike Diedrich
DOI:10.1055/s-1990-26946
日期:——
Oxocarbons and Related Compounds; Part 15. Meerwein-Arylation of Semisquaric Acid and Semisquaric Amides. A General Method for the Preparation of 3-Aryl-4-hydroxy- and 3-Amino-4-aryl-3-cyclobutene-1,2-diones Meerwein-arylation of semisquaric acid (1) and semisquaric amides 4 has been found to afford general routes to 3-aryl-4-hydroxy-3-cyclobutene-1,2-diones 3 and 3-amino-4-aryl-3-cyclobutene-1,2-diones 5, respectively.
TFA-catalyzed ring transformation of 4-hydroxycyclobutenone: A simple and general route for preparation of 3-substituted 4-aminofuran-2(5H )-ones †
作者:Jie Wang、Xin Jiang、Ming Chen、Zongming Ge、Yuefei Hu、Hongwen Hu
DOI:10.1039/b004654j
日期:——
positions, respectively, to yield 4-substituted 3-aminocyclobutene-1,2-diones 14. Reduction of compounds 14 with NaBH4 yield 2-substituted 3-amino-4-hydroxycyclobutenones 15 in high yields. By ring transformation of products 15 catalyzed by TFA, a simple and generalroute for the preparation of 3-substituted 4-aminofuran-2(5H)-ones 4 is developed. A two-step mechanism is proposed to describe the ring