13733-20-5Relevant articles and documents
Direct Observation and Analysis of the Halo-Amino-Nitro Alkane Functional Group
Crocker, Michael S.,Foy, Hayden,Tokumaru, Kazuyuki,Dudding, Travis,Pink, Maren,Johnston, Jeffrey N.
supporting information, p. 1248 - 1264 (2019/05/08)
Conventional amide synthesis is a mainstay in discipline-spanning applications, and it is a reaction type that historically developed as a singular paradigm when considering the carbon-nitrogen bond-forming step. Umpolung amide synthesis (UmAS) exploits the unique properties of an α-halo nitroalkane in its reaction with an amine to produce an amide. The “umpolung” moniker reflects its paradigm-breaking C–N bond formation on the basis of evidence that the nucleophilic nitronate carbon and electrophilic nitrogen engage to form a tetrahedral intermediate (TI) that is an unprecedented functional group, a 1,1,1-halo-amino-nitro alkane (HANA). Studies probing HANA transience have failed to capture this (presumably) highly reactive intermediate. We report here the direct observation of a HANA, its conversion thermally to an amide functionality, and quantitative analysis of this process using computational techniques. These findings validate the HANA as a functional group common to UmAS and diverted UmAS, opening the door to its targeted use and creative manipulation. Functional groups are the “cities” on a map of mechanistic pathways (the “roads”), and chemists use functional groups as pivot points to valuable chemical intermediates. Functional groups are defined by a collection of atoms, and variations on these atoms can define a group's behavior, especially its stability and reaction trajectory. Once recognized as a distinct arrangement of atoms connected by a discrete pathway to a specific product, new opportunities are presented to manipulate its conversion to new outcomes. Herein, we prepare and characterize an intermediate containing halogen (F), amine (N), and nitro (NO2) at an alkane (C-sp3) carbon and establish it as a precursor to both amide and oxadiazole products, thereby codifying two key mechanistic pathways united by the HANA functional group. A computationally driven study of the pathway connecting these species identifies additional diversion points, and the HANA itself might be targeted with novel entry points. Preparation and characterization of a new functional group, HANA, is described. A study of its thermal conversion to amide provides direct evidence for its role as a TI in UmAS, and this interconversion along several possible pathways is studied by computational analysis. The experimental and energy landscape outlined by these studies illustrates that the HANA can be manipulated to acyclic and heterocyclic products, setting the stage for future rational reaction design.
Synthesis of N-Acyl carbamates and oxazolidinones using HClO 4-SiO2 as catalyst under solvent-free conditions
Yang, Li Juan,Yang, Yuping,Dong, Ruoyi
experimental part, p. 1085 - 1087 (2011/12/16)
Silica supported perchloric acid catalyzes efficiently the reaction of carbamates and oxazolidinones with anhydrides in the presence of silica sulfuric acid under solvent-free conditions. All the reactions were done at room temperature and the N-acyl carb
Reaction of C-alkylated heterocyclic ketene aminals with diethyl azodicarboxylate: Synthesis of polyfunctionalized quaternary carbon derivatives and their thermal fragmentation
Zhao, Mei-Xin,Wang, Zhe-Ming,Wang, Mei-Xiang,Yan, Chun-Hua,Huang, Zhi-Tang
, p. 7791 - 7796 (2007/10/03)
Five-membered ring C-alkylated heterocyclic ketene aminals react with diethyl azodicarboxylate to give the quaternary carbon-containing adducts in moderate to excellent yields while the six-membered analogs afford imidazo[1,5-a]pyrimidin-6-one derivatives
