New Protocol for Masking and Unmasking Vicinal Hydroxyl and Formyl Groups in 6-Hydroxyarene-1,3-dicarboxaldehydes

Abstract

A simple and efficient protocol is revealed for the masking and unmasking of an α-hydroxyl benzaldedyde group in aromatic dialdehydes by forming keto-enamine Schiff bases and subsequent unmasking using NaN₃/DMF.

Keywords:

• Enamine
• 2-hydroxy benzaldehydes
• masking
• NMR spectroscopy
• regioselectivity
• Schiff bases
• unmasking

ACKNOWLEDGMENTS

Authors are grateful to the director, Central Drug Research Institute (CDRI), Lucknow, India, for constant encouragement during the drug development program and to Sophisticated Analytical Instrument Facility (SAIF) for 300-MHz NMR, IR, and mass spectral data. J. N. R. and A. K. are thankful to the University Grants Commission (UGC) and Council of Scientific and Industrial Research (CSIR), New Delhi, respectively, for financial support.

Notes

^a Structures confirmed by IR, ¹H NMR and mass spectroscopy.

CDRI Communication No. 7316.