Application of Directed Metalationin Synthesis. Part 5:Synthesis of CondensedSulfur-Oxygen Heterocycle via Novel Anionic Rearrangement-Cyclisation
作者:Asish De、Chandrani Mukherjee、Sukanta Kamila
DOI:10.1055/s-2003-40822
日期:——
Introduction of the methyl sulfanyl function in the ortho-position to O-carbamate functionality under standard directed metalation condition was followed by side-chain deprotonation with sec-butyl lithium at -78 °C. Upon warming to room temperature, the deprotonated species underwent intramolecular anionic rearrangement to afford N,N-diethyl-2-hydroxyarylthioacetamides. The rearranged products were cyclised with hot glacial acetic acid to afford condensed oxathiin-2-ones in excellent yields.
Application of directed metalation in synthesis. Part 6: A novel anionic rearrangement under directed metalation conditions leading to heteroannulation
作者:Tarun Kanti Pradhan、Chandrani Mukherjee、Sukanta Kamila、Asish De
DOI:10.1016/j.tet.2004.04.033
日期:2004.6
from easily available phenols is described. The key step in this synthesis is a hitherto unreported anionic rearrangement under directed metalation conditions. The rearrangement occurs after side chain deprotonation of a methyl sulfanyl group by an O-carbamate directed metalating group and the reaction mixture is kept at room temperature for 8–12 h. Acid-mediated cyclisation of the rearranged product