Competitive binding of peptides containing basic amino acids to disrupt or prevent the Tat– TAR interaction could result in diminished transcription as well as translation and hence constitutes an alternative way of controlling HIV replication. Therefore, we synthesized guanidinium and amino containing amino acids, based on a proline or an alanine scaffold. The introduction of the guanidinium moiety was best accomplished using 1H-pyrazole-1- ...