Practical synthesis of 5-amino-6-chlorochroman-8-carboxylic acid – a key intermediate for several potent 5-HT4 receptor agonists

Synthetic routes for 5-amino-6-chlorochroman-8-carboxylic acid 1 a key intermediate for several potent 5-HT4 agonists have been explored. An efficient, high yielding, and a concise synthetic route has been established with significant modifications to the earlier reported synthetic protocols, where we have avoided the use of toxic and corrosive reagents and reduced the reaction temperature from reflux to room temperature wherever is possible. We have also reduced the number of steps to reach the target compound and avoided the use of silica gel column purifications.