1237706-56-7Relevant academic research and scientific papers
Photochemically Switching Diamidocarbene Spin States Leads to Reversible Büchner Ring Expansions
Perera, Tharushi A.,Reinheimer, Eric W.,Hudnall, Todd W.
supporting information, p. 14807 - 14814 (2017/10/24)
The discovery of thermal and photochemical control by Woodward and Hoffmann revolutionized how we understand chemical reactivity. Similarly, we now describe the first example of a carbene that exhibits differing thermal and photochemical reactivity. When a singlet ground-state N,N'-diamidocarbene 1 was photolyzed at 380 nm, excitation to a triplet state was observed. The triplet-state electronic structure was characteristic of the expected biradical σ1pπ1 spin configuration according to a combination of spectroscopic and computational methods. Surprisingly, the triplet state of 1 was found to engage a series of arenes in thermally reversible Büchner ring expansion reactions, marking the first examples where both cyclopropanation and ring expansion of arenes were rendered reversible. Not only are these photochemical reactions different from the known thermal chemistry of 1, but the reversibility enabled us to perform the first examples of photochemically induced arene exchange/expansion reactions at a single carbon center.
Elucidating the mechanism of reversible oxiranations via magnetization transfer spectroscopy
Chase, Daniel T.,Moerdyk, Jonathan P.,Bielawski, Christopher W.
supporting information, p. 5510 - 5513 (2013/01/15)
The reversible [2 + 1] cycloadditions between an N,N′-diamidocarbene (DAC) and eight aldehydes were examined using NMR spectroscopy. Variable temperature magnetization transfer experiments revealed higher exchange rates and lower activation barriers when electron-deficient aldehydes were employed. Likewise, competitive equilibrium studies indicated a thermodynamic preference for electron-deficient aryl and sterically unhindered alkyl aldehydes compared to more electron-rich or bulkier substrates. Collectively, these and other data collected were consistent with the oxiranation process proceeding in an asynchronous manner.
Alkyne and reversible nitrile activation: N, N'-diamidocarbene-facilitated synthesis of cyclopropenes, cyclopropenones, and azirines
Moerdyk, Jonathan P.,Bielawski, Christopher W.
scheme or table, p. 6116 - 6119 (2012/05/07)
We report the synthesis of a variety of diamidocyclopropenes by combining an isolable and readily accessible N,N'-diamidocarbene (DAC) with a range of alkynes (nine examples, 68-97% yield). Subsequent hydrolysis of selected cyclopropenes afforded the corresponding cyclopropenones or α,β- unsaturated acids, depending on the reaction conditions. In addition, the combination of a DAC with alkyl or aryl nitriles was found to form 2H-azirines in a reversible manner (four examples, Keq = 4-72 M-1 at 30 °C in toluene).
Ammonia N-H activation by a N,N′-diamidocarbene
Hudnall, Todd W.,Moerdyk, Jonathan P.,Bielawski, Christopher W.
supporting information; experimental part, p. 4288 - 4290 (2010/08/06)
The synthesis and characterization of N,N′-dimesityl-4,6-diketo-5,5- dimethylpyrimidin-2-ylidene is reported; this crystalline N,N′- diamidocarbene was found to split ammonia and engage in other reactions not exhibited by typical N-heterocyclic carbenes.
