Enantioselective Synthesis of Densely Functionalized Pyranochromenes via an Unpredictable Cascade Michael-Oxa-Michael-Tautomerization Sequence
作者:Qiao Ren、Yaojun Gao、Jian Wang
DOI:10.1002/chem.201002490
日期:2010.12.10
A surprising example of enantioselectivecascade Michael–oxa‐Michael–tautomerization reactions of malononitrile and benzylidenechromanones has been developed. In this case, malononitrile functions as both nucleophile and electrophile. Meanwhile, a simple bifunctional indane amine–thiourea catalyst has been discovered to promote this process to afford high yields (up to 99%) and high to excellent enantiomeric
Facile synthesis of spiro chromanone-tetrahydrothiophenes with three contiguous stereocenters via sulfa-Michael/aldol cascade reactions
作者:Ya-Jian Hu、Xiao-Bing Wang、Su-Yi Li、Sai-Sai Xie、Kelvin D.G. Wang、Ling-Yi Kong
DOI:10.1016/j.tetlet.2014.11.026
日期:2015.1
A novel sulfa-Michael/aldol cascade reaction of (E)-3-arylidenechroman-4-ones with 1,4-dithiane-2,5-diol has been developed. This method provides a new practical and facile approach to 4′-hydroxy-2′-aryl-4′,5′-dihydro-2′H-spiro[chroman-3,3′-thiophen]-4-ones with three contiguous stereocenters in high yields. The transformation is atom-economic with good to excellent diastereoselectivities.
Spiropyrazolines have been synthesized by 1,3-dipolar cycloaddition of an 2-arylidene-1-tetralone, 3-arylidene-chromanones, -1-thiochromanones, and -flavanones with diazomethane. The relative configuration and stereochemistry of the products have been determined by means of one-dimensional difference N.O.E. measurements. It is shown that ring-closure reaction is regioselective, yielding stereohomogeneous
Fused heterocycles.<b>8</b>. An efficient procedure for the stereoselective synthesis of<i>trans</i>-2,3,3a,4-tetrahydro-3-aryl-2-phenyl[1]benzopyrano[4,3-<i>c</i>]pyrazoles and their [1]benzothiopyrano analogues
作者:Albert Lévai
DOI:10.1002/jhet.5570350103
日期:1998.1
Stereoselective synthesis of trans-2,3,3a,4-tetrahydro-3-aryl-2-phenyl[1]benzopyrano[4,3-c]pyrazoles 13–18 and their [1]benzothiopyrano analogues 19–24 has been performed by the reaction of 3-arylidenechromanones 1–6 and 3-arylidene-1-thiochromanones 7–12 with phenylhydrazine in hot pyridine. The structure and stereochemistry of the compounds prepared have been elucidated by ir, lH and 13C nmr measurements
的立体选择性合成反式-2,3,3a,4-四氢-3-芳基-2-苯基[1]苯并吡喃并[4,3- c ^ ]吡唑13-18和它们的[1]苯并噻喃并类似物19-24已被执行通过在热吡啶中3-芳基苯并二氢杂蒽酮1-6和3-芳基-1-硫代并苯并二氢杂苯并酮7-12与苯肼反应。通过ir,l H和13 C nmr测量已经阐明了所制备化合物的结构和立体化学。
Iodine-promoted sequential Michael and oxidative dehydrogenation processes: synthesis of trisubstituted methanes containing a coumarin and a chromone ring
作者:Ya-Jian Hu、Neng Jiang、Sai-Sai Xie、Su-Yi Li、Jin-Shuai Lan、Ling-Yi Kong、Xiao-Bing Wang
DOI:10.1016/j.tet.2015.08.056
日期:2015.10
An iodine-promoted convenient and environmentally friendly sequential method for the synthesis of trisubstituted methanes bearing a coumarin and a chromone ring is described. The remarkable features of this approach include avoidance of metals, working under air, employment of readily available starting materials, good functional group tolerance and simple operation. (C) 2015 Elsevier Ltd. All rights reserved.