An unprecedented external oxidant-free electrochemical protocol for 1, 3-oxohydroxylation of donor-acceptor cyclopropane is disclosed. The strategy encompasses the activation of the labile π-electron cloud of the aryl ring to cleave the strained C sp 3 À C sp 3 bond of cyclopropane to afford the β-hydroxy ketones via insertion of molecular oxygen. More significantly, based on the detailed mechanistic investigations and cyclic voltammetry experiments, a plausible mechanism is proposed.The magnificent journey of the most strained carbocycle named cyclopropane began long back in the 1970s. [1] The fundamentals laid by the frontiers have enabled the scientific community to exploit them for the construction of several complex molecular architectures cleverly. Bearing the ring strain of 115 KJ mol À 1 with an inefficient orbital overlap induces a significant amount of π-character in the bent CÀ C bonds of Cylclopropanes. [2] Further, the introduction of the donor and acceptor groups at the vicinal position of these CÀ C bonds induces a push-pull effect which polarizes the cycloalkane. [3] The previous decade has encountered a huge renaissance in the area of donor-acceptor cyclopropanes (DACs). [4] However, most of these documented protocols rely on the concept of Lewis [5] or Bronsted acid [6] catalysis, which cleaves the CÀ C bond in a heterolytic fashion and renders a zwitterionic species. [4] These 1,3-dipole species have been utilized for several cycloadditions, [7] rearrangements, [8] and ring-opening reactions. [9] Among them, 1,3-bifunctionalization of these DACs are still rare and relatively underexplored. However, there are several reports which demonstrate that these 1,3-dipoles can be seized with amines, [10a] azides, [10b] phenols, [10c] thiols [10d] etc. wherein, the ensuing anion traps the proton. In 2011, Sparr and Gilmour manifested the enantioselective 1,3-dichlorination of cyclopropane carbaldehyde in an organocatalytic fashion. [11] Later, in 2014, Werz and coworkers disclosed the ring-opening 1,3-dichlorination in the presence of iodobenzene dichloride (Scheme 1a). [12a] Followed by this, in 2017, the same group documented the reactivity of DACs with chalcogenyl chloride and bromides (Scheme 1b). [12b-c] In continuation to the endeav-[a
The synthesis of paracetamol still relies on multistep protocols involving the utilization of a stoichiometric amount of oxidizing/reducing or other corrosive agents. Herein we report a regioselective electrochemical Ritter-type reaction at the C(sp 2 )−H of unprotected phenol toward the environmentally benign and direct synthesis of paracetamol. The reaction proceeds under exogenous oxidant-and catalyst-free conditions. The protocol is scalable, can be deployed to a variety of phenols, and offers a sustainable alternative for the synthesis of paracetamol.
Rearrangement reactions constitute a critical facet of synthetic organic chemistry and demonstrate an attractive way to take advantage of existing structures to access various important molecular frameworks. Electroorganic chemistry has...
The electronically unbiased arylcyclopropane functionalization has always been a challenge to organic chemists, and the emergence of donor-acceptor cyclopropanes (DACs) has not only vehemently overshadowed them but still dominates the...
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