Development of Human Calcitonin Gene-Related Peptide (CGRP) Receptor Antagonists. 1. Potent and Selective Small Molecule CGRP Antagonists. 1-[ N 2 -[3,5-Dibromo- N -[[4-(3,4-dihydro-2(1 H )-oxoquinazolin-3-yl)-1- piperidinyl]carbonyl]- d -tyrosyl]- l -lysyl]-4-(4-pyridinyl)piperazine: The First CGRP Antagonist for Clinical Trials in Acute Migraine †