Photocatalytic Synthesis of Oxetane Derivatives by Selective CH Activation

Abstract

The selective CA C H T U N G T R E N N U N G (sp 3 ) À H activation at position 2 in oxetanes has been accomplished by decatungstate photocatalysis under mild conditions. The resulting a-oxy radicals were trapped by electronpoor olefins resulting in the smooth preparation of 2-substituted oxetanes. The chemoselectivity in hydrogen abstraction in substituted oxetanes containing other H donating groups, such as CH 2 OH, CH 2 OAc and CHO, has been demonstrated in intramolecular models.

Electrostatic Effects Accelerate Decatungstate-Catalyzed C–H Fluorination Using [18F]- and [19F]NFSI in Small Molecules and Peptide Mimics

“…Near-UV irradiation of DT gives rise to a singlet excited state that quickly decays to a more long-lived reactive intermediate (wO) capable of single electron transfer or HAT from aliphatic compounds. , Pioneering studies by Hill , demonstrated that alkane dehydrogenation, epimerization, and carbonylation can be readily affected using DT catalysis. Fagnoni, , Albini, Ravelli, , and Ryu ,,, have demonstrated that DT-promoted C­(sp 3 )–H abstraction can be coupled with several useful C–C, C–Si, and C–N bond-forming reactions. In addition, Noël and Orfanopolous , have studied alkane and alcohol oxidation by photoactivated DT.…”

Formal Giese addition of C(sp3)–H nucleophiles enabled by visible light mediated Ni catalysis of triplet enone diradicals

“…However, the scope of this reaction was restricted to N -arylisoquinolines, since polymerizable or β-substituted acceptors proved less effective or unsuitable. Furthermore, Albini 9 and Fagnoni 10 reported a series of analogous reactions of α-oxy C–H bonds, but these reactions required the use of UV light, and only limited donor–acceptor combinations were applicable. Moreover, Fagnoni and Melchiorre reported the addition of dioxolanyl or α-amino radicals to iminium intermediates; however, this process was restricted to cyclic enones.…”

Direct α‐Arylation of Ethers through the Combination of Photoredox‐Mediated CH Functionalization and the Minisci Reaction

“…[23] However, at the present time, there are few synthetic methods that allow for the facile introduction of oxetane in a direct and routine fashion into medicinal agents. [23,24] We initially found that the use of this strained ring system led to an oxetanyl radical that underwent ring-opening polymerization under our optimal aqueous/acid conditions. Gratifyingly, when the coupling of oxetane and isoquinoline was carried out in MeCN (0.05 M) with the addition of ( n Bu) 4 NCl to help solubilize the persulfate anion, a useful 42% yield of the desired product was obtained (product 32 ).…”