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Lewis Acid/Oxidant as Rapid Regioselective Halogenating Reagent System for Direct Halogenation of Fused Bi‐/Tri‐cyclic Hetero‐Aromatic Congeners via C ( s p 2 ) −H bond Functionalization
Author(s) -
Yadav Ravi Kant,
Sharma Richa,
Gautam Deepak,
Joshi Jyoti,
Chaudhary Sandeep
Publication year - 2021
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.202100156
Subject(s) - halogenation , chemistry , regioselectivity , reagent , surface modification , halogen bond , combinatorial chemistry , lewis acids and bases , halogen , organic chemistry , catalysis , alkyl
Herein, we report the identification of new and fast halogenating reagent system consisting of Lewis acid AlX 3 [X=Cl, Br, I] as a halogen source in the presence of tert ‐butyl hydroperoxide (TBHP) which has been utilized for the direct regioselective halogenation on various fused bi‐/tri‐cyclic hetero‐aromatic congeners 3 a – q , 7 a – d , 8 and 9 viaC( sp 2 ) −H bond functionalization. The operationally simple protocol is quite fast and does not require the external halogenation source at 110 °C in 20–60 minutes and furnished halogenated fused heterocycles 4 a – p , 5 a – k , 6 a – l , 10 a – i , 11 a , 12 a – b in up to 96% yields. The gram‐scale synthesis, wide substrate scope, functional group tolerance, control experiments and application to further derivatization/functionalization for C−C bond formation further highlights the versatility of the developed methodology as well as the compatibility of the new catalyst. The combination of Lewis acid (AlX 3 ) as a halogen source and TBHP (oxidant) as a halogenating reagent system is the first account for the direct regioselective halogenation of several fused bi‐/tri‐cyclic hetero‐aromatic congeners viaC( sp 2 ) −H bond functionalization.