Organocatalytic Activation of Donor–Acceptor Cyclopropanes: A Tandem (3 + 3)-Cycloaddition/Aryl Migration toward the Synthesis of Enantioenriched Tetrahydropyridazines
Metal‐Free Ring Opening Cyclization of Cyclopropane Carbaldehydes and
<i>N</i>
‐Benzyl Anilines: An Eco‐Friendly Access to Functionalized Benzo[
<i>b</i>
]azepine Derivatives
作者:Raghunath Dey、Prabal Banerjee
DOI:10.1002/adsc.201801714
日期:2019.6.18
Herein, we report a p‐toluenesulfonic acid (PTSA) initiated mild and user‐friendly ring opening/domino ring opening cyclization reaction (depends on substituent present in N‐benzyl aniline) of cyclopropane carbaldehyde and N‐benzyl aniline towards the formation of substituted 4‐amino butanal/2,3‐dihydro‐1H‐benzo[b]azepine. The product dihydro‐1H‐benzo[b]azepine was also converted into the corresponding
在此,我们报道了对丙烷磺酸和环丙烷苯甲醛与N-苄基苯胺的对甲苯磺酸(PTSA)引发的温和且用户友好的开环/多米诺环开环反应(取决于N-苄基苯胺中存在的取代基) 4-氨基丁醛/ 2,3-二氢-1 H-苯并[ b ]氮杂。产物二氢-1 H-苯并[ b ]氮杂也被转化为相应的四氢-1 H-苯并[ b ]氮杂。
Regioselective Brønsted Acid-Catalyzed Annulation of Cyclopropane Aldehydes with <i>N</i>′-Aryl Anthranil Hydrazides: Domino Construction of Tetrahydropyrrolo[1,2-<i>a</i>]quinazolin-5(1<i>H</i>)ones
作者:Priyanka Singh、Navpreet Kaur、Prabal Banerjee
DOI:10.1021/acs.joc.9b03170
日期:2020.3.6
synthesis of tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one derivatives was achieved by reacting cyclopropane aldehydes with N'-aryl anthranil hydrazides in the presence of p-toluene sulfonic acid (PTSA). The transformation involves domino imine formation and intramolecular cyclization to form 2-arylcyclopropyl-2,3-dihydroquinolin-4(1H)-one, followed by nucleophilic ring opening of the cyclopropyl ring to form
Accessing Dihydro-1,2-oxazine via Cloke–Wilson-Type Annulation of Cyclopropyl Carbonyls: Application toward the Diastereoselective Synthesis of Pyrrolo[1,2-<i>b</i>][1,2]oxazine
作者:Pankaj Kumar、Rakesh Kumar、Prabal Banerjee
DOI:10.1021/acs.joc.0c00531
日期:2020.5.15
A convenient additive-free synthesis of dihydro-4H-1,2-oxazines via a Cloke-Wilson-type ring expansion of the aryl-substituted cyclopropane carbaldehydes with the hydroxylamine salt is introduced. Comparatively less active cyclopropyl ketones also follow a similar protocol if supplemented by catalytic p-toluene sulfonic acid monohydrate. The transformation is performed in an open-to-air flask as it
Enantioselective Copper-Catalyzed 1,5-Cyanotrifluoromethylation of Vinylcyclopropanes
作者:Zi-Qi Zhang、Xiang-Yu Meng、Jie Sheng、Quan Lan、Xi-Sheng Wang
DOI:10.1021/acs.orglett.9b03012
日期:2019.10.18
A copper-catalyzedenantioselective 1,5-cyanotrifluoromethylation of vinylcyclopropanes has been developed using a radical relay strategy. This asymmetric reaction has demonstrated high enantioselective control, broad substrate scope, and mild conditions. Initiated by the in situ generated CF3 radical from Togni’s reagent, this method offers a new solution for remote enantioselective bifunctionalization
Metal-free domino Cloke-Wilson rearrangement-hydration-dimerization of cyclopropane carbaldehydes: A facile access to oxybis(2-aryltetrahydrofuran) derivatives
作者:Raghunath Dey、Shruti Rajput、Prabal Banerjee
DOI:10.1016/j.tet.2020.131080
日期:2020.4
demonstrated a metal-free transformation of cyclopropane carbaldehydes to oxybis(2-aryltetrahydrofuran) derivativesvia a domino Cloke-Wilson rearrangement-hydration-dimerization sequence. Commercially inexpensive p-toluene sulfonic acid (PTSA) was used as a Brønsted acid catalyst, and reactions were conducted in an open-flask. Detection of reaction intermediates were carried to get an insight into the