- Scale-up of the green synthesis of azacycloalkanes and isoindolines under microwave irradiation
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A green approach to N-heterocyclization reactions ranging in scale from 20 mmol to 1 mol performed under microwave irradiation in open vessels has been investigated. By using water as the solvent and no transition metal catalysts, N-heterocycles are formed in a fraction of the time needed for conventional synthesis of these compounds. The obtained yields indicate that reactions can be performed at atmospheric pressure using the same reaction conditions as the corresponding sealed-vessel reactions. Single-mode and multimode microwave cavities have been used for open-vessel synthesis without changing reaction times producing similar yields.
- Barnard, T. Michael,Vanier, Grace S.,Collins Jr., Michael J.
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- Oxidative Desymmetrization of Isoindolines Realized by tert -Butyl Nitrite (TBN) Initiated Radical sp 3C-H Activation Relay (CHAR)
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An oxidative desymmetrization of isoindolines was realized by TBN initiated radical sp 3C-H activation relay (CHAR), providing a series of ω-hydroxylactams in high yields. This reaction exhibits broad substrate scope and functional group tolerance, and even N -alkyl iso-indolines can be well tolerated. The mechanistic study shows that the C-H bond oxidation, dioxygen trapping and intramolecular 1,5-H shift might be the key steps to achieve the oxidative desymmetrization.
- Sun, Zheng,Shao, Yu,Zhang, Shuwei,Zhang, Yuxian,Yuan, Yu,Jia, Xiaodong
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p. 1663 - 1671
(2021/02/01)
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- Aqueous N-heterocyclization of primary amines and hydrazines with dihalides: Microwave-assisted syntheses of N-azacycloalkanes, isoindole, pyrazole, pyrazolidine, and phthalazine derivatives
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The synthesis of nitrogen-containing heterocycles from alkyl dihalides (ditosylates) and primary amines and hydrazines via a simple and efficient cyclocondensation in an alkaline aqueous medium that occurs under microwave irradiation is described. This improved greener synthetic methodology provides a simple and straightforward one-pot approach to the synthesis of a variety of heterocycles, such as substituted azetidines, pyrrolidines, piperidines, azepanes, N-substituted 2,3-dihydro-1H-isoindoles, 4,5-dihydropyrazoles, pyrazolidines, and 1,2-dihydrophthalazines.
- Ju, Yuhong,Varma, Rajender S.
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p. 135 - 141
(2007/10/03)
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