Mono-Acylation of Diamine via Ionic Immobilization

Significance

A novel method for the controlled mono-protection of diamines via ionic immobilization is described. Thus, diamines 1 (0.15 mmol) were ionically immobilized on a sulfonic acid functionalized silica gel 2 to give 3. The solid-phase protection of 3 with a variety of protecting agents 4 (0.45 mmol) was performed in CH₂Cl₂ to afford products 5 that were treated with NH₃ (2 N in MeOH, 3 mL) to give the corresponding mono-protected piperazine or homopiperazine compounds 6 in 28-75% yield (11 examples).