15875-99-7Relevant articles and documents
Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
supporting information, p. 5217 - 5221 (2017/04/27)
Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
On the Mechanism of Base-Induced Gas-Phase Elimination Reactions of Ethers
Koning, Leo J. de,Nibbering, Nico M. M.
, p. 1715 - 1722 (2007/10/02)
For the base-induced gas-phase elimination reactions of diethyl ether and cis- and trans-1-tert-butyl-4-methoxy-cyclohexane the kinetic isotope and leaving group effects have been determined as functions of the base strength using the method of Fourier transform ion cyclotron resonance mass spectrometry.The results are interpreted in terms of a variable E2 transition-state structure.Increasing the base strength causes the transition state to shift toward the carbanion or E1cb region of the E2 spectrum, which is also a general phenomenon in the condensed phase.Moreover, it appears that the elimination reactions most readily proceed via a transition state in which the β hydrogen and leaving group are periplanar.If the substrate does not easily allow such a relationship, the transition state is found to shift toward the carbenium ion or E1 region of the E2 spectrum where the geometric restrictions of the substrate are less perceptible.The concept of syn/anti dichotomy is used to explain the formation of tree and solvated alkoxide anions in the reactions induced by OH-.Anti elimination is believed to result in the formation of free alkoxide.Syn elimination, which takes advantage of the electrostatic interaction between the base and leaving group, is held responsible for the formation of solvated alkoxide.The importance of base/leaving group association in the transition state of the syn elimination is demonstrated by the low yield of solvated alkoxide in the reaction of OH-, solvated by a dimethylamine molecule, with diethyl ether.Finally, it seems that the selectivity of gas-phase elimination reactions is determined by not only the relative heights of the intrinsic reaction barriers, but also the relative stabilities of the ion/molecule complexes preceding the reaction barriers.
13C Nuclear Magnetic Resonance Spectra of Methoxycyclohexane Derivatives. Rotamer Populations about C-OMe Bonds as indicated by 13C Chemical Shifts of Methoxy- and Ring-carbons and 3JC,H Coupling Constants
Haines, Alan H.,Shandiz, Mohammad Seyedi
, p. 1671 - 1678 (2007/10/02)
Methoxy 13C chemical shifts in methoxycyclohexane derivatives may be rationalized in terms of rotamer populations about the C-OMe bond and δ1-effects caused by steric interaction of the methoxy-group with substituents at the neighbouring 2- and 6-positions.Information on rotamer populations is obtained also from the 13C chemical shifts of C-2 and C-6, and from the three-bond coupling between the proton at C-1 and the methoxy-carbon atom.
