DMAP Catalyzed Domino Rauhut–Currier Cyclization Reaction between Alkylidene Pyrazolones and Nitro-olefins: Access to Tetrahydropyrano[2,3-<i>c</i>]pyrazoles
作者:Nimisha Bania、Buddhadeb Mondal、Sounak Ghosh、Subhas Chandra Pan
DOI:10.1021/acs.joc.0c02871
日期:2021.3.5
Herein, we employ unsaturated pyrazolones in the Rauhut–Currier reaction for the first time. A domino Rauhut–Currier cyclization reaction has been developed between unsaturated pyrazolones and nitro-olefins. The trisubstituted tetrahydropyrano[2,3-c]pyrazoles were obtained in moderate to high yields with excellent diastereoselectivities. A few applications including a synthesis of disubstituted tetrahydropyrano[2
在本文中,我们首次在Rauhut-Currier反应中使用了不饱和吡唑啉酮。在不饱和吡唑啉酮和硝基烯烃之间发展了多米诺Rauhut-Currier环化反应。三取代四氢吡喃并[2,3- c ]吡唑以中等至高收率获得,具有非对映选择性。已经证明了包括合成二取代的四氢吡喃并[2,3- c ]吡唑在内的一些应用。还使用手性DMAP催化剂研究了该方法的初步催化不对称形式。
Enantioselective aminocatalytic synthesis of tetrahydropyrano[2,3-c]pyrazoles via a domino Michael-hemiacetalization reaction with alkylidene pyrazolones
作者:Rajendra Maity、Subhas Chandra Pan
DOI:10.1039/c7ob02170d
日期:——
An enantioselectiveorganocatalytic domino Michael-hemiacetalization reaction between alkylidene pyrazolones and cyclic ketones/pentanal has been revealed. The fused tetrahydropyranopyrazole products having three contiguous stereocentres were obtained with perfect diastereoselectivities and in moderate to good yields with good to high enantioselectivities. Also, few synthetic transformations of the
Enantio‐ and Diastereoselective Synthesis of β<i>‐</i>Aryl<i>‐</i>β<i>‐</i>pyrazolyl α‐Amino Acid Esters via Copper‐Catalyzed Reaction of Azomethine Ylides with Benzylidenepyrazolones
stereoselective synthesis of unnatural chiral β‐aryl‐β‐pyrazolyl α‐amino acidesters via copper‐catalyzed addition reactions of azomethine ylides with benzylidenepyrazolones bearing two contiguous stereogenic centers was developed. A 1H‐pyrazol‐5‐ol was introduced by the aromatization of 3H‐pyrazol‐3‐one in the reaction. The transformation operated at room temperature and afforded β‐1H‐pyrazol‐5‐ol‐α‐amino
Highly Diastereo- and Enantioselective Synthesis of Spiro-tetrahydrofuran-pyrazolones via Organocatalytic Cascade Reaction between γ-Hydroxyenones and Unsaturated Pyrazolones
作者:Buddhadeb Mondal、Rajendra Maity、Subhas Chandra Pan
DOI:10.1021/acs.joc.8b00781
日期:2018.8.3
The first diastereo- and enantioselective synthesis of spiro-tetrahydrofuran-pyrazolones is reported via organocatalytic asymmetric cascade oxa-Michael/Michael reaction between γ-hydroxyenones and unsaturated pyrazolones. Bifunctional squaramide catalyst was found to be effective for this reaction. With 10 mol % of catalyst, excellent results were attained for a variety of spiropyrazolones under mild
Lewis acid catalyzed annulation of spirocyclic donor–acceptor cyclopropanes with <i>exo</i>-heterocyclic olefins: access to highly functionalized bis-spirocyclopentane oxindole frameworks
作者:Kuldeep Singh、Sourav Pramanik、Trevor A. Hamlin、Biplab Mondal、Dinabandhu Das、Jaideep Saha
DOI:10.1039/c9cc03393a
日期:——
Lewisacidcatalyzedhighly efficient [3+2] annulation of spirocyclic Donor–Acceptorcyclopropanes (DACs) with exo-heterocyclic olefins is reported to furnish various biologically relevant dispiro-2,3-dioxopyrrolidine[cyclopentane]oxindole and dispiropyrazolone[cyclopentane]oxindole frameworks. This report highlights the use of oxindole-activated spiro-DACs as potential synthons to access complex dispirocarbocyclic