A Sc(OTf)3-catalyzed highly diastereoselective one-pot sequential [3 + 3] dipolar cycloaddition reaction of aldehyde or ketone, N-alkyl hydroxylamine, and spirocyclopropyl oxindole is developed, allowing facile construction of spirocyclic oxindole-tetrahydro-1,2-oxazines with sufficient structural diversity. The corresponding catalytic enantioselective one-pot protocol of aldehydes is also reported
Metal-free C(sp<sup>3</sup>)–H bond sulfonyloxylation of 2-alkylpyridines and alkylnitrones
作者:Chang-Sheng Wang、Pierre H. Dixneuf、Jean-François Soulé
DOI:10.1039/c8ob01075g
日期:——
Pyridin-2-ylmethyl tosylate derivatives are obtained in high yields from 2-alkylpyridine 1-oxides via a [3,3]-sigmatropicrearrangement of the adduct between 2-alkylpridine 1-oxides with benzenesulfonyl chlorides. Moreover, alkylnitrones also undergo [3,3]-sigmatropicrearrangement to give α-tosylated ketones after hydrolysis. Substitution reactions with nucleophiles then lead to diverse useful functionalizations
作者:Joyann S. Barber、Evan D. Styduhar、Hung V. Pham、Travis C. McMahon、K. N. Houk、Neil K. Garg
DOI:10.1021/jacs.5b13304
日期:2016.3.2
two stereogenic centers. DFT calculations of stepwise and concerted reaction pathways are used to rationalize the observed selectivities. Moreover, the strategic manipulation of nitrone cycloadducts demonstrates the utility of this methodology for the assembly of compounds bearing multiple heterocyclic units. These studies showcase the exploitation of a traditionally avoided reactive intermediate in chemical
A novel multiheteroatom (N, O and P) [3,3]-sigmatropic rearrangement is disclosed, based on two important types of organophosphates, 2-(N-heteroaryl) methyl phosphates and α-keto phosphates, being accessed smoothly and efficiently.
Photocatalytic Reductive Fluoroalkylation of Nitrones
作者:Vyacheslav I. Supranovich、Vitalij V. Levin、Marina I. Struchkova、Alexander D. Dilman
DOI:10.1021/acs.orglett.7b03987
日期:2018.2.2
A method for the addition of fluorinated groups to nitrones using an iridium photocatalyst and ascorbic acid as a stoichiometric reducing agent is described. The reaction proceeds through the generation of fluorinated radicals by single-electron reduction of fluorinated alkyl iodides with an iridium complex mediated by visible light. Besides perfluorinated reagents, partially fluorinated alkyl iodides