Modified Pictet–Spengler reaction. A highly diastereoselective approach to 1,2,3-trisubstituted-1,2,3,4-tetrahydro-β-carbolines using perhydro-1,3-heterocycles

A flexible variant of the Pictet–Spengler reaction employing oxazinanes as synthetic equivalents of several carbonyl compounds has been developed. Using acid catalyzed one pot condensation of perhydro-1,3-heterocycles various 1,3-disubstituted and 1,2,3-trisubstituted-1,2,3,4-tetrahydro-β-carbolines (THBCs) have been synthesized diastereoselectively.