Stereocontrolled Oxyselenation Studies on 1,4-Dihydropyridines: Synthesis of Trans-2-hydroxy (or Alkoxy) 3-Phenylseleno-1,2,3,4-tetrahydropyridines

Abstract

In view of the versatile chemistry and important applications of organoselenium compounds, the introduction of selenium and oxygen functionalities to 1,4-dihydropyridines 4a–d has been achieved. Thus, the natural tendency of 1,4-dihydropyridines 4a–d to undergo biomimetic oxidation to afford pyridinium salts can be switched off through the use of reagents that interact electrophilically with the enamine moiety present in the system. Electrophilic interaction of N-phenylselenophthalimide (N-PSP) with N-alkyl-1,4-dihydropyridines 4a–d in the presence of tetrahydrofuran/H₂O and alcohol (methanol or ethanol) stereoselectively leads to the corresponding trans-2-hydroxy (or alkoxy) 3-phenylseleno-1,2,3,4-tetrahydropyridines 5a–k in satisfactory yields (40–90%).

Keywords:

• Dihydropyridine
• N-phenylselenophthalimide (N-PSP)
• seleniranium ion
• tetrahydropyridine

ACKNOWLEDGMENT

We thank the Department of Science and Technology and the University Grant Commission, New Delhi, for financial support.