Novelroute for the construction of chromans from benzylic and aliphatic alcohols in the presence of NaHSO4/SiO2 has been developed. In this reaction, substituted olefins are formed from benzylic and aliphatic alcohols and then converted to chromans through intramolecular cyclization. Twenty novel chromans were synthesized by this simple procedure.
Brønsted Acid-Catalyzed, Highly Enantioselective Addition of Enamides to In Situ<i>-</i>Generated<i>ortho</i>-Quinone Methides: A Domino Approach to Complex Acetamidotetrahydroxanthenes
作者:Satyajit Saha、Christoph Schneider
DOI:10.1002/chem.201406044
日期:2015.2.2
The highly enantioselective conjugate addition of enamides and enecarbamates to in situ‐generated ortho‐quinone methides, upon subsequent N,O‐acetalization, gives rise to acetamido‐substituted tetrahydroxanthenes with generally excellent enantio‐ and diastereoselectivities. A chiral BINOL‐based phosphoric acid catalyst controls the enantioselectivity of the carbon–carbon bond‐forming event. The products
Enantioselective Addition of Thiols to ortho-Quinone Methides Catalyzed by Chiral Phosphoric Acids
作者:Jianwei Sun、Zengwei Lai
DOI:10.1055/s-0035-1560546
日期:——
The first Bronsted acidcatalyzed enantioselective addition of thiols to the in situ generated ortho-quinone methides (o-QMs) is described. Complementary to the chiral amine catalyzed approach, the present reaction employs a chiral phosphoric acid as the catalyst. The readily available o-hydroxybenzyl alcohols serve as the atom-economical precursors of o-QMs to react with tritylthiol with moderate
A green synthesis of unsymmetrical triarylmethanes via indium (III) triflate catalyzed Friedel Crafts alkylation of o -hydroxy bisbenzylic alcohols under solvent free conditions
作者:Sankalan Mondal、Deblina Roy、Manoj Kumar Jaiswal、Gautam Panda
DOI:10.1016/j.tetlet.2017.11.049
日期:2018.1
Using indium (III) triflate as a mild Lewis acid catalyst, the Friedel Crafts alkylation of o-hydroxy bisbenzylic alcohols with aromatic/heteroaromatic arenes under solvent free conditions was achieved to give the corresponding unsymmetrical triarylmethanes in high yields (up to 80% yield). Calculation of the different green metrics for the above reaction revealed it to have high atom economy (94–96%)
A base-promoted cascade reaction of α,β-unsaturated <i>N</i>-tosylhydrazones with <i>o</i>-hydroxybenzyl alcohols: highly regioselective synthesis of <i>N-sec</i>-alkylpyrazoles
作者:Lian-Mei Chen、Juan Zhao、An-Jie Xia、Xiao-Qiang Guo、Ya Gan、Chuang Zhou、Zai-Jun Yang、Jun Yang、Tai-Ran Kang
DOI:10.1039/c9ob01780a
日期:——
N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20 : 1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α