The Use of Cyanic Acid in Glacial Acetic Acid. Ii. The Addition of Cyanic Acid on Benzalazine.

Intra–Intermolecular Criss‐cross Cycloaddition of Nonsymmetrical Allenylazines with Fluorinated Enones as an Initial Step in the Synthesis of4H‐Pyrrolo[1,2‐b]pyrazoles

“…[2] The first reaction of this type between two equivalents of PhNCO and benzaldazine afforded a new compound with two fused five-membered heterocycles. [3] In the first step of the reaction, a 1,3-dipole is formed. Although the mechanism [4] of the reaction was proposed in 1963, it was proved eleven years later when a stable 1,3-dipole intermediate was isolated.…”

“…The heterodiene and the dipolarophile entering the reaction are individual molecules. [3,7,8] The second group may be considered as an intramolecular cycloaddition. Depending upon the regioselectivity of the reaction, we can observe formation of laterally [9,10] or centrally [11,12] fused heterocyclic compounds.…”

Aromatic glyoxalimines in criss-cross cycloaddition reactions

“…In our short communication [1], we wrote about criss-cross cycloadditions to some 1,4-disubstituted 1,4-diazabuta-1,3-dienes (1) as an easy and cheap way to obtain mixed 1,4-disubstituted 5-thioxoperhydroimidazo [4,5-d]imidazole-2-ones (3) (monothioglycoluriles). These products appeared always as the major products, being in huge excess of the symmetrically formed molecules (2). Such behaviour is extremely developed in the 4-methoxyphenyl substituted derivative (1) a derivative with aromatic substitution.…”

Synthesis of 1,2λ5‐Azaphosphoridines

“…An intermediate formation of (3) during decomposition of (6) can be excluded because, although (3) and (6) have comparable thermal stability, (3) is not formed on thermolysis of (6) in either a stationary or a flow system (detection by VPC).…”