Visible-Light-Enhanced Ring Opening of Cycloalkanols Enabled by Brønsted Base-Tethered Acyloxy Radical Induced Hydrogen Atom Transfer-Electron Transfer

Abstract

A metal-free ring opening/halogenation of cycloalkanols, which combines both PPO/TBAX oxidant system and blue LEDs irradiation, is presented. This method produces diverse γ, δ, and even more remotely halogenated ketones in moderate to excellent yields under mild conditions. Interestingly, experimental and computational studies demonstrate the novel ring size-dependent concerted/stepwise (four-/five- to eight-membered rings) hydrogen atom transfer-electron transfer induced by Brønsted base-tethered acyloxy radical, which indicates distinct advantages brought by the cyclic structure of diacyl peroxides.

Radical‐Promoted C−C Bond Cleavage: A Deconstructive Approach for Selective Functionalization

“…[37] Later, Shi and co-workers [38] disclosed an induced hydrogen-atom transfer/electron transfer (HAT-ET) as an alternative to the above methods.Here,aradical/anion intermediate enhances the ability to promote HATt o accomplish the homolytic cleavage of the OÀHb ond. [37] Later, Shi and co-workers [38] disclosed an induced hydrogen-atom transfer/electron transfer (HAT-ET) as an alternative to the above methods.Here,aradical/anion intermediate enhances the ability to promote HATt o accomplish the homolytic cleavage of the OÀHb ond.…”

Synthesis of Functionalized Cyclobutane‐Fused Naphthalene Derivatives via Cascade Reactions of Allenynes with tert‐Butyl Nitrite

“…On the other hand, 3-nitro-1-phenyl-1,2-dihydrocyclobuta[a]naphthalene-1,4-diol (3 a) was obtained in 50% yield (Table 1, entry 1). This is mainly due to the fact that compounds containing either the cyclobutanol moiety as embedded in 3 a [11,12] or the naphthalene-1,2dione unit as present in 4 a are useful precursors toward various kinds of fine chemicals. Although A was not obtained, the unprecedented formation of 3 a and 4 a from the reaction of 1 a with 2 is no less interesting.…”

“…Although A was not obtained, the unprecedented formation of 3 a and 4 a from the reaction of 1 a with 2 is no less interesting. [11][12][13][14] To improve its efficiency and selectivity, several parameters possibly affecting this reaction were screened. [13,14] In addition, they are also prevalent in naturally occurring and man-made compounds with potent biological activities.…”

“…This is mainly due to the fact that compounds containing either the cyclobutanol moiety as embedded in 3 a [11,12] or the naphthalene-1,2dione unit as present in 4 a are useful precursors toward various kinds of fine chemicals. Further studies in varying the loadings of TEMPO and TBN did not give more positive results (entries [12][13][14][15]. A literature search revealed that reliable and sustainable methods for their synthesis are very limited.…”

“…Although A was not obtained, the unprecedented formation of 3 a and 4 a from the reaction of 1 a with 2 is no less interesting. This is mainly due to the fact that compounds containing either the cyclobutanol moiety as embedded in 3 a [11,12] or the naphthalene-1,2dione unit as present in 4 a are useful precursors toward various kinds of fine chemicals. [13,14] In addition, they are also prevalent in naturally occurring and man-made compounds with potent biological activities.…”