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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(48):15511-15515
A visible‐light‐driven Minisci protocol that employs an inexpensive earth‐abundant metal catalyst, decacarbonyldimanganese Mn2(CO)10, to generate alkyl radicals from alkyl iodides has been developed. This Minisci protocol is compatible with a wide array of sensitive functional groups, including oxetanes, sugar moieties, azetidines, tert ‐butyl carbamates (Boc‐group), cyclobutanes, and spirocycles. The robustness of this protocol is demonstrated on the late‐stage functionalization of complex nitrogen‐containing drugs. Photophysical and DFT studies indicate a light‐initiated chain reaction mechanism propagated by .Mn(CO)5. The rate‐limiting step is the iodine abstraction from an alkyl iodide by .Mn(CO)5. 相似文献
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J. Luke Koniarczyk Jacob W. Greenwood Juan V. Alegre‐Requena Robert S. Paton Andrew McNally 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15024-15028
A pyridine–pyridine coupling reaction has been developed between pyridyl phosphonium salts and cyanopyridines using B2pin2 as an electron‐transfer reagent. Complete regio‐ and cross‐selectivity are observed when forming a range of valuable 2,4′‐bipyridines. Phosphonium salts were found to be the only viable radical precursors in this process, and mechanistic studies indicate that the process does not proceed through a Minisci‐type coupling involving a pyridyl radical. Instead, a radical–radical coupling process between a boryl phosphonium pyridyl radical and a boryl‐stabilized cyanopyridine radical explains the C?C bond‐forming step. 相似文献
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Bartosz Bieszczad Luca Alessandro Perego Paolo Melchiorre 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17034-17039
We report herein a visible light‐mediated C?H hydroxyalkylation of quinolines and isoquinolines that proceeds via a radical path. The process exploits the excited‐state reactivity of 4‐acyl‐1,4‐dihydropyridines, which can readily generate acyl radicals upon blue light absorption. By avoiding the need for external oxidants, this radical‐generating strategy enables a departure from the classical, oxidative Minisci‐type pattern and unlocks a unique reactivity, leading to hydroxyalkylated heteroarenes. Mechanistic investigations provide evidence that a radical‐mediated spin‐center shift is the key step of the process. The method's mild reaction conditions and high functional group tolerance accounted for the late‐stage functionalization of active pharmaceutical ingredients and natural products. 相似文献
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