A study of some pyridopyrazines and pyridopyrimidines

The d‐ and l‐forms of 2 H ‐octahydropyrido[1,2‐a]pyrazine (I) have been prepared and their absolute configurations established. These configurations were confirmed by an optical rotary dispersion study. The infrared spectra of 2 H ‐octahydropyrido[1,2‐a]pyrazine (I), lH‐octahydropyrido[ 1,2‐a]pyrimidine (11) and 2H‐octahydropyrido[ 1,2‐c]pyrimidine (111) were compared with the infrared spectrum of quinolizidine. All of these spectra showed the Bohlmann bands characteristic of a trans ring structure. A few derivatives of these ring systems have been prepared.