l-Proline-Catalysed One-Pot aza-Diels–Alder Reaction in Water: Regioselective Synthesis of Spiro(isoxazolo[5,4-b]pyridine-5,5′-pyrimidine) Derivatives

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1195-1198 ◽  
Author(s):  
Yuvaraj Dommaraju ◽  
Somadrita Borthakur ◽  
Dipak Prajapati

A simple and efficient l-proline-catalysed synthesis of spiro(isoxazolo[5,4-b]pyridine-5,5′-pyrimidine) derivatives in water has been accomplished through a pseudo five-component one-pot domino aza-Diels–Alder reaction involving 3-amino crotanonitrile, hydroxylamine hydrochloride, aromatic aldehydes and barbituric acids. The main advantages of the present method are mild reaction conditions, modest purification process involving no chromatographic techniques and high yields. The protocol is a good alternative to prepare spiro derivatives with readily available starting materials, which makes the method highly attractive.

Synlett ◽  
2021 ◽  
Author(s):  
Izuru Tsuchimochi ◽  
Shuhei Hori ◽  
Yasuo Takeuchi ◽  
Masahiro Egi ◽  
Tomo-o Satoh ◽  
...  

Starting from readily available tertiary alcohols, four different reactions (i.e., a 1,3-migration of a hydroxy group, kinetic resolution, racemization, and an intramolecular Diels–Alder reaction) took place under the co-catalysis of lipase and oxovanadium compounds in a one-pot process to produce multisubstituted tricyclic carbon frameworks in high yields and high enantioselectivities. The key to the success of this process was the discovery that the silyl group attached to the terminal carbon of the vinyl moiety completely controls the direction of hydroxy group migration.


2011 ◽  
Vol 8 (s1) ◽  
pp. S420-S424 ◽  
Author(s):  
T. S. R. Prasanna ◽  
K. Mohana Raju

T3P was found to be an efficient catalyst for the Aza-Diels–Alder reactions of aldimines with dihydropyran or dihydrofuran to afford the corresponding pyrano-and furo [3,2-c]quinolines in high yields with high diastereoselectivity in a short period of time.


2021 ◽  
Vol 17 ◽  
pp. 2425-2432
Author(s):  
Ren-Jie Fang ◽  
Chen Yan ◽  
Jing Sun ◽  
Ying Han ◽  
Chao-Guo Yan

The p-TsOH-catalyzed Diels–Alder reaction of 3-(indol-3-yl)maleimides with chalcone in toluene at 60 °C afforded two diastereoisomers of tetrahydropyrrolo[3,4-c]carbazoles, which can be dehydrogenated by DDQ oxidation in acetonitrile at room temperature to give the aromatized pyrrolo[3,4-c]carbazoles in high yields. On the other hand, the one-pot reaction of 3-(indol-3-yl)-1,3-diphenylpropan-1-ones with chalcones or benzylideneacetone in acetonitrile in the presence of p-TsOH and DDQ resulted in polyfunctionalized carbazoles in satisfactory yields. The reaction mechanism included the DDQ oxidative dehydrogenation of 3-(indol-3-yl)-1,3-diphenylpropan-1-ones to the corresponding 3-vinylindoles, their acid-catalyzed Diels–Alder reaction and sequential aromatization process.


2021 ◽  
Author(s):  
Ren-Jie Fang ◽  
Chen Yan ◽  
Jing Sun ◽  
Ying Han ◽  
Chao-Guo Yan

p-TsOH catalyzed Diels-Alder reaction of 3-(indol-3-yl)maleimides with chalcone in toluene at 60 oC afforded two diastereoisomers of tetrahydropyrrolo[3,4-c]carbazoles, which can be dehydrogenated by DDQ oxidation in acetonitrile at room temperature to give the aromatized pyrrolo[3,4-c]carbazoles in high yields. On the other hand, the one-pot reaction of 3-(indol-3-yl)-1,3-diphenylpropan-1-ones with chalcones in acetonitrile in the presence of p-TsOH and DDQ resulted in polyfunctionalized carbazoles in satisfactory yields. The reaction mechanism included DDQ oxidative dehydrogenation of 3-(indol-3-yl)-1,3-diphenylpropan-1-ones to the corresponding 3-vinylindoles, its acid-catalyzed Diels-Alder reaction and sequential aromatization process.


2014 ◽  
Vol 10 (6) ◽  
pp. 951-960
Author(s):  
Orazio Attanasi ◽  
Luca Bianchi ◽  
Maurizio D’Auria ◽  
Gianfranco Favi ◽  
Fabio Mantellini ◽  
...  

Synthesis ◽  
2020 ◽  
Vol 52 (13) ◽  
pp. 1947-1958
Author(s):  
Tsutomu Konno ◽  
Gen Egashira ◽  
Chihiro Kajimoto ◽  
Takuto Kataoka ◽  
Shigeyuki Yamada

On treating 1,3,4-tribromo-1,1,2,2-tetrafluorobutane, readily prepared from commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene, with 3.3 equivalents of LHMDS at 0 °C in THF, the corresponding lithium acetylide could be prepared quantitatively. The acetylide reacted well with various aldehydes, ketones, or chlorosilanes to give the corresponding acetylene derivatives in high yields. It was also found that various iodoarenes could participate in the cross-coupling reaction with the zinc acetylide, readily prepared from the lithium acetylide and ZnCl2·TMEDA complex, in the presence of Pd(PPh3)4 to bring about the adducts in high yields. Thus-obtained acetylene derivatives underwent smooth Diels–Alder reaction with various 1,3-dienes to afford the corresponding 1,4- or 1,3-cyclohexadiene derivatives. In addition, it was revealed that the oxidative aromatization of the resulting cyclohexadiene derivatives with DDQ took place very smoothly, providing the multi-substituted benzene derivatives having a tetrafluoro­ethylene group.


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