The Crisscross Addition on Conjugate Systems. The Action of Cyanic Acid, Thiocyanic Acid and Isocyanates on Azines.

Abstract

Introduction.Thiele in his comprehensive study of the unsaturated compounds1 concludes that, as a rule, with a conjugate system of double bonds, more especially C = C -C = C and C = C -C = 0 addition takes place on the 1,4 position rather than on the 1,2 or 3,4 position. Subsequently it developed that Thiele's conclusions were not justified, for, as shown by Straus,2 *e. g., the addition of bromine on the system C = C -C = C takes place on both the 1,2 and 1,4 positions. Staudinger* has shown conjugate system, C = C -C = O. W. J. Hale, of the University of Michigan, has by letter taken issue with Bailey and Moore as to the constitution of their CeHsCH = N -N = 1 "Die Ketene," p. 2 (1912).2 Ann., 336, 95 (1907).

Criss-cross Cycloadditions on Ketazines Derived from Alicyclic Ketones

“…The crude product was filtered off, washed with water, acetone and finally with ether. [1,2,4]triazolo [1,2-a] [1,2,4] [1,2,4]triazolo [1,2-a] [1,2,4] Criss-cross cycloaddition of KNCS in CH 3 COOH -General procedure KSCN (2.5 g, 0.0257 mol) was dissolved in CH 3 COOH (20 mL) at room temperature. Then ketazine (0.005 mmol) was added and the reaction mixture was stirred for 1 hour.…”

“…The suspension was poured in H 2 O (200 ml) and the precipitated product was filtered off. [1,2,4]triazolo [1,2-a] [1,2,4] …”

“…The first article described the cycloaddition of cyanic acid to benzalazine [1]. The second dealt with cycloaddition of cyanic, isothiocyanic acid and phenyl isocyanate with aromatic aldazines (prepared from benzaldehyde, 3-nitrobenzaldehyde, cinnamaldehyde and furfuraldehyde) [2]. A general mechanism for these reactions is shown in Scheme 1.…”

“…A general mechanism for these reactions is shown in Scheme 1. Aldazines react as dipoles with two molecules of a dipolarophile to form heterocyclic compounds with two fused five-membered rings -in this case tetrahydro- [1,2,4]triazolo [1,2-a] [1,2,4]triazole-1,5-diones substituted in positions 3 and 7. Since then, a number of papers have appeared listing examples of criss-cross cycloadditions of various dipolarophiles and aldazines [3].…”

“…They react with potassium cyanate and ammonium thiocyanate in the presence of acetic acid to form spirocyclic perhydro [1,2,4] …”