Molecular iodine catalyst promoted synthesis of chromans and 4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling
作者:Mayuri M. Naik、Durga P. Kamat、Santosh G. Tilve、Vijayendra P. Kamat
DOI:10.1016/j.tet.2014.05.093
日期:2014.8
Molecular iodine as an inexpensive catalyst is described in the construction of 2-substituted or 2,2-disubstituted chromans and 4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling. For the synthesis of chromans, phenols and allylic alcohols were refluxed in chloroform in presence of 20 mol % I-2 while [3+3] cyclocoupling of phenols and cinnamic acids proceeded to give 4-aryl-3,4-dihydrobenzopyran-2-ones using 30 mol % I-2. Later reaction occurs via a tandem hydroarylation-esterification process at 120-130 degrees C under solvent free conditions. Chromans were obtained in 20-92% yields and substituted 4-aryl-3,4-dihydrobenzopyran-2-ones were obtained in 5-85% yields. (C) 2014 Elsevier Ltd. All rights reserved.
Chenault, Jacques; Dupin, Jean-Francois E., Heterocycles, 1983, vol. 20, # 3, p. 437 - 443
作者:Chenault, Jacques、Dupin, Jean-Francois E.
DOI:——
日期:——
CHENAULT, J.;DUPIN, J. -F. E., HETEROCYCLES, 1983, 20, N 3, 437-443
作者:CHENAULT, J.、DUPIN, J. -F. E.
DOI:——
日期:——
A convenient synthesis of dihydrocoumarins from phenols and cinnamic acid derivatives
A facile procedure for synthesis of dihydrocoumarin derivatives was described. Although the yield of the products in the reaction of phenols with acrylates in trifluoroacetic acid in the presence of Pd(OAc)2 giving coumarins was found to be very low, dihydrocoumarin derivatives were obtained in good to high yields in the absence of Pd(OAc)2 when ethyl cinnamates bearing electron-donating groups were
Stereochemical Control in the Reduction of 2-Chromanols
作者:Kelin Li、Kumar Vanka、Ward H. Thompson、Jon A. Tunge
DOI:10.1021/ol061727g
日期:2006.10.1
silane reductants and 2,4-trans-chromans using the smaller silane PhSiH(3). The stereochemical outcome has been rationalized on the basis of a Curtin-Hammett kinetic situation arising from hydride delivery to two different conformations of an intermediate oxocarbenium ion. This method provides a powerful way to control the relative stereochemistry of these substructures which are prevalent in bioactive