Browsing by Author "Ravelli, Davide"

Now showing 1 - 6 of 6

Cooperative Polar/Steric Strategy in Achieving Site-Selective Photocatalyzed C(sp(3))-H Functionalization
(2017-06-27)
Yamada, Keiichi
;
Fukuyama, Takahide
;
Fujii, Saki
;
Ravelli, Davide
;
Fagnoni, Maurizio
Synergistic control over the S(H)2 transition states of hydrogen abstraction exploiting polar and steric effects provides a promising cooperative strategy for site-selective C(sp(3))-H functionalization using decatungstate anion photocatalysis. By using this photocatalytic approach, the C-H bonds of substituted lactones and cyclic ketones were functionalized selectively. In the remarkable case of 2-isoamyl 4-tert-butyl cyclohexanone (1t) bearing five methyl, five methylene, and three methine C-H bonds, one methine C-H bond in the isoamyl tether was selectively functionalized.
Photocatalyzed Site-Selective C(sp(3))-H Functionalization of Alkylpyridines at Non-Benzylic Positions
(2017-12-01)
Fukuyama, Takahide
;
Nishikawa, Tomohiro
;
Yamada, Keiichi
;
Ravelli, Davide
;
Fagnoni, Maurizio
Tetrabutylammonium decatungstate (TBADT)-photocatalyzed C-H functionalization of alkylpyridines was investigated. Unlike alkylbenzene counterparts, alkylation of alpha-C-H bonds did not proceed for the reaction of 2- and 4-alkylpyridines and reluctantly proceeded for 3-alkylpyridines, which allow site-selective C(sp(3))-H functionalization at nonbenzylic positions. The observed nonbenzylic site selectivities are rationalized by the polar inductive effects of pyridyl groups in the S-H(2) transition states. Consecutive gamma-functionalization and alpha-bromofunctionalization were successfully carried out in selected cases.
Site-Selective C-H Functionalization by Decatungstate Anion Photocatalysis: Synergistic Control by Polar and Steric Effects Expands the Reaction Scope
(2018-01-01)
Ravelli, Davide
;
Fagnoni, Maurizio
;
Fukuyama, Takahide
;
Nishikawa, Tomohiro
;
Ryu, Ilhyong
The synergistic control of the S(H)2 transition states of hydrogen abstraction by polar and steric effects provides a promising strategy in achieving site-selective C(sp(3))-H functionalization under decatungstate anion photo catalysis. By using this photocatalytic approach, the C-H bonds of alkanes, alcohols, ethers, ketones, amides, esters, nitriles, and pyridylalkanes were functionalized site-selectively. In the remarkable case of a 2,4-disubstituted cyclohexanone bearing five methyl, five methylene, and three methine C-H bonds, one methine C-H bond in the isoamyl tether was selectively functionalized.
Site-selectivity in TBADT-photocatalyzed C(sp(3))-H Functionalization of Saturated Alcohols and Alkanes
(2018-01-01)
Fukuyama, Takahide
;
Yamada, Keiichi
;
Nishikawa, Tomohiro
;
Ravelli, Davide
;
Fagnoni, Maurizio
Site-selectivity in C(sp(3))-H functionalization of aliphatic alcohols and alkanes was studied using the decatungstate anion as a photocatalyst. In the case of aliphatic alcohols, C-H bond alpha to the hydroxy group was preferentially functionalized. The alpha-site-selectivity is rationalized by polar effects imparted by the hydroxy group in the S(H)2 transition states. In contrast, C-H functionalization of alkanes was largely affected by steric effects.
Versatile cross-dehydrogenative coupling of heteroaromatics and hydrogen donors via decatungstate photocatalysis
(2017)
Quattrini, Matteo C.
;
Fujii, Saki
;
Yamada, Keiichi
;
Fukuyama, Takahide
;
Ravelli, Davide
A facile sunlight-induced derivatization of heteroaromatics via photocatalyzed C-H functionalization in amides, ethers, alkanes and aldehydes is described. Tetrabutylammonium decatungstate (TBADT) was used as the photocatalyst and allowed to carry out the process under mild conditions.
Versatile cross-dehydrogenative coupling of heteroaromatics and hydrogen donors via decatungstate photocatalysis
(2017)
Quattrini, Matteo C.
;
Fujii, Saki
;
Yamada, Keiichi
;
Fukuyama, Takahide
;
Ravelli, Davide
A facile sunlight-induced derivatization of heteroaromatics via photocatalyzed C-H functionalization in amides, ethers, alkanes and aldehydes is described. Tetrabutylammonium decatungstate (TBADT) was used as the photocatalyst and allowed to carry out the process under mild conditions.