Substituted ureas, acylureas and sulphonylureas prodn - by reacting a substituted cyanamide with a cpd forming a carbonium ion

摘要

Ureas, acylureas and sulphonylureas of formula (I): (in which A = H or a gp. R1-X where X = -CO- or -SO2- and R1 = opt. substd. aliphatic or aromatic (cyclo)alkyl gp., aralkyl gp., alkoxy gp., aryloxy or etheroxy gp., R2 = H or opt. substd. alkyl, cycloalkyl, aralkyl or aryl and R3 = H or a gp. derived from a sec. or tert. alcohol, esp. a tert. butyl gp., such that if R2 = H, R3 = org. alkyl gp. and if R3 = H, R2 = organic, opt. substituted (cyclo) alkyl, aralkyl or aryl gp.), are made by reacting a cyanamide of formula: in the presence of a catalyst with a cpd. which easily forms a carbocation of formula R3+. The process is simple, economical and gives good yields of urea cpds. previously difficult to synthesise. The cpd. giving a carbocation R3+ may be e.g. a tert. alcohol, a sec. alcohol and/or an unsatd. cpd. The catalyst used is e.g. H2SO4 or a Lewis acid, and the reaction may be carried out in a solvent for the cyanamide. Typical starting materials are 2,3-dimethylphenylcyanamide, 2,3-dimethylphenyltosylcyanamide, m-tolyl-p-nitrophenylsulphonylcyanamide, etc. Examples of the end products (I) are 1-benzoyl-1-phenyl-3-tert. butylurea, 1-m-tolyl-1-p-nitrophenylsulphonyl-3-tert. butylurea, etc. 4.9 g tert. butylcyanamide was added to 20 ml tert. butanol and 12.5 ml BF3 etherate added. The mixt. was stirred for 1 hour at room temp. and poured into 100 g ice water. The ppte. was filtered off, washed and dried to yield 4.19 g (48.7%) N,N'-di-tert. butylurea.