Switching the chemoselectivity in the amination of 4-chloroquinazolines with aminopyrazoles.

The chemoselectivity in the amination of 4-chloroquinazolines with 3-amino-1H-pyrazoles was studied. Under the conditions of Pd(2)(dba)(3)/Xantphos/Na(2)CO(3), 4-chloroquinazolines underwent selective amination with the cyclic secondary amino group of 3-amino-1H-pyrazoles, whereas 4-chloroquinazolines were exclusively aminated with the primary amino group of 3-amino-1H-pyrazoles via S(N)Ar substitution in the presence of HCl.