13837-45-1Relevant articles and documents
Synthesis, Purification, and Rotational Spectroscopy of (Cyanomethylene)Cyclopropane—An Isomer of Pyridine
Esselman, Brian J.,Kougias, Samuel M.,Zdanovskaia, Maria A.,Woods, R. Claude,McMahon, Robert J.
, p. 5601 - 5614 (2021)
The gas-phase rotational spectrum of (cyanomethylene)cyclopropane, (CH2)2C═CHCN, generated by a Wittig reaction between the hemiketal of cyclopropanone and (cyanomethylene)triphenylphosphorane, is presented for the first time. This small, highly polar nitrile is a cyclopropyl-containing structural isomer of pyridine. The rotational spectra of the ground state and two vibrationally excited states were observed, analyzed, and least-squares fit from 130 to 360 GHz. Over 3900 R-, P-, and Q-branch, ground-state rotational transitions were fit to low-error, partial octic, A- and S-reduced Hamiltonians, providing precise determinations of the spectroscopic constants. The two lowest-energy vibrationally excited states, ν17and ν27, form a Coriolis-coupled dyad displaying smalla- andb-type resonances. Transitions for these two states were measured and least-squares fit to a two-state, partial octic, A-reduced Hamiltonian in the Irrepresentation with nine Coriolis-coupling terms (Ga,GaJ,GaK,GaJJ,Fbc,FbcJ,FbcK,Gb, andGbJ). The observation of many resonant transitions and nine nominal interstate transitions enabled a very accurate and precise energy difference between ν17and ν27to be determined: ΔE17,27= 29.8975453 (33) cm-1. The spectroscopic constants presented herein provide the foundation for future astronomical searches for (cyanomethylene)cyclopropane.
Experimental and Computational Studies on Rh(I)-Catalyzed Reaction of Siloxyvinylcyclopropanes and Diazoesters
Feng, Sheng,Wang, Kang,Ping, Yifan,Wang, Jianbo
, p. 21032 - 21039 (2020)
The Rh(I)-catalyzed reaction of siloxyvinylcyclopropanes and diazoesters leads to the formation of siloxyvinylcyclobutane and 1,4-diene derivatives. With [Rh(cod)Cl]2 as the catalyst, the formation of 1,4-diene was favored over the formation of siloxyvinylcyclobutane. By changing the catalyst to [Rh(cod)2OTf], siloxyvinylcyclobutane derivatives are formed with excellent chemoselectivities and in moderate to good yields. The alkene products are also obtained as single E configured isomers. A detailed mechanism for this transformation is proposed on the basis of mechanistic experiments and DFT calculations. The effect of catalysts on the chemoselectivity of these reactions is also examined computationally.
Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β-Lactams
Jang, Yujin,Johnson, J. Drake,Jung, Myunggi,Lindsay, Vincent N. G.,Poteat, Christopher M.,Williams, Rachel G.
supporting information, p. 18655 - 18661 (2020/08/21)
Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability. Reported here is the enantioselective synthesis of 1-sulfonylcyclopropanols, as stable yet powerful equivalents of the corresponding cyclopropanone derivatives, by α-hydroxylation of sulfonylcyclopropanes using a bis(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives. Both the electronic and steric nature of the sulfonyl moiety, which serves as a base-labile protecting group and confers crystallinity to these cyclopropanone precursors, were found to have a crucial impact on the rate of equilibration to the corresponding cyclopropanone. The utility of these cyclopropanone surrogates is demonstrated in a mild and stereospecific formal [3+1] cycloaddition with simple hydroxylamines, leading to the efficient formation of chiral β-lactam derivatives.
Synthesis of Cyclopentenones with Reverse Pauson-Khand Regiocontrol via Ni-Catalyzed C-C Activation of Cyclopropanone
Jang, Yujin,Lindsay, Vincent N. G.
supporting information, p. 8872 - 8876 (2020/12/02)
A formal [3 + 2] cycloaddition between cyclopropanone and alkynes via Ni-catalyzed C-C bond activation has been developed, where 1-sulfonylcyclopropanols are employed as key precursors of cyclopropanone in the presence of trimethylaluminum. The transformation provides access to 2,3-disubstituted cyclopentenones with complete regiocontrol, favoring reverse Pauson-Khand products, where the large substituent is located at the 3-position of the ring. In the process, the trimethylaluminum additive is thought to play multiple roles, including as a Br?nsted base triggering the equilibration to cyclopropanone and liberation of methane, as well as a source of Lewis acid to activate the carbonyl group toward Ni-catalyzed C-C activation.
