Search

Olcegepant is one of the most potent and selective small molecule CGRP antagonists for the treatment of migraine headaches. Herein, we describe a new and efficient synthesis of the key piperidinyl dihydroquinazolinone (PDQ) fragment of olcegepant. PDQ plays a key role in the activity of CGRP antagonists. Primary improvements over existing methods include a high-yielding reductive amination step, greater overall yield, and operational simplicity. Coupling of PDQ to a d -tyrosine derivative effectively produced over one half of the total molecular structure of olcegepant. A unique tandem deprotection-nucleophilic addition sequence was also applied to the coupling of Fmoc-PDQ with phenyl isocyanate.

Far-red cyanine fluorophores find extensive use in modern microscopy despite modest quantum yields. To improve the photon output of these molecules, we report a synthetic strategy that blocks the major deactivation pathway: excited-state trans-to-cis polyene rotation. In the key transformation, a protected dialdehyde precursor undergoes a cascade reaction to install the requisite tetracyclic ring system. The resulting molecules exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. Moreover, these compounds recover from hydride reduction with dramatically improved efficiency. These observations enable efficient single-molecule localization microscopy in oxygenated buffer without addition of thiols. Enabled by modern organic synthesis, these studies provide a new class of far-red dyes with promising spectroscopic and chemical properties.