Oxokohlenstoffe und verwandte Verbindungen; 14. Mitteilung.¹ Chemie der Semiquadratsäure: Reaktive Semiquadratsäure-Abkömmlinge und deren Umsetzung mit N-Nucleophilen

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.