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Alkylidenecyanamidium Salts. α‐Bromination of Carbodiimides
Author(s) -
Jochims Johannes C.,
Rahman Mohammed Abdur
Publication year - 1984
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19841170208
Subject(s) - chemistry , halogenation , sulfonium , alkylation , medicinal chemistry , phosphorus pentachloride , alkyl , sulfide , salt (chemistry) , tetrafluoroborate , organic chemistry , isocyanide , chloride , halide , imine , catalysis , ionic liquid
Carbodiimides ( 15 ) of type react with N ‐bromosuccinimide (NBS) to afford unstable alkylidenecyanamidium bromides ( 18 ) which undergo von Braun elimination of R – Br giving the alkylidenecyanamides 19 if R is a tertiary alkyl group. Reaction of carbodiimides ( 15 ) of the type with N ‐bromosuccinimide results in bromination not only of the α but also of the β position, the latter occuring via De Kimpe halogenation 16) of 18 . Stable cyanamidium salts 18 could be obtained when compounds 19 were alkylated with tert ‐butyl chloride or 1‐chloroadamantane and antimony pentachloride. The compound 18c was also obtained from N ‐chlorobenzophenone imine, tert ‐butyl isocyanide, and antimony pentachloride. Alkylation of the N ‐cyanoguanidine 19r with triethyloxonium tetrafluoroborate afforded the salt 18r . Reactions of the alkylidenecyanamidium salts 18 with a sulfide (yielding a sulfonium salt and 19 ), with amines (to give the alkylideneguanidinium salts 23 ) and with alcohols (affording the alkylideneuronium salts 22 ) are described. The structures of the new formal heterocumulenes are discussed.