- Understanding α,β-unsaturated imine formation from amine additions to α,β-unsaturated aldehydes and ketones: An analytical and theoretical investigation
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A combination of in situ IR spectroscopy (ReactIR) and DFT calculations have been used to understand what factors govern the selectivity in the addition of primary amines to α,β-unsaturated aldehydes and ketones, i.e., 1,2- versus 1,4-addition. It has been found that the 1,2-addition products (α,β-unsaturated imines following addition and elimination) usually predominate for most systems. However, exceptions, such as methyl vinyl ketone, selectively give 1,4-addition products. This has been rationalized by DFT calculations that show that major conformational effects are involved, controlled mainly by steric effects of carbonyl substituents, resulting in a model that provides simple and predictable preparation of α,β- unsaturated imines for in situ utilization in synthesis.
- Calow, Adam D. J.,Carbó, Jorge J.,Cid, Jessica,Fernández, Elena,Whiting, Andrew
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supporting information
p. 5163 - 5172
(2014/06/23)
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- Highly regioselective control of 1,2-addition of organolithiums to α,β-unsaturated compounds promoted by lithium bromide in 2-methyltetrahydrofuran: A facile and eco-friendly access to allylic alcohols and amines
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Very high regioselective 1,2-addition of organolithiums to α,α-unsaturated carbonyl-like compounds (ketones, aldehydes, and imines) in the presence of LiBr was achieved by carrying out reactions in the sustainable solvent 2-methyltetrahydrofuran. Excellent yields (in isolated product) of allylic alcohols and allylic amines were recovered under a simple experimental procedure at 0 °C.
- Pace, Vittorio,Castoldi, Laura,Hoyos, Pilar,Sinisterra, José Vicente,Pregnolato, Massimo,Sánchez-Montero, Ma. José
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supporting information; experimental part
p. 2670 - 2675
(2011/04/23)
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- Halogenated Ketenes. 38. Cycloaddition of α,β-Unsaturated Imines with Ketenes To Yield Both β- and δ-Lactams
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The cycloaddition of various types of α,β-unsaturated imines with diphenyl- and dichloroketenes yields both (2 + 2) and (4 + 2) cycloaddition products, i. e., β-lactams and δ-lactams, respectively.The cycloaddition products are dependent upon substitution in the imine and the ketene.The δ-lactams derived from dichloroketene are easily dehydrochlorinated to the corresponding 2-pyridones.All of the results are consistent with a two-step cycloaddition process involving a dipolar intermediate.
- Brady, William T.,Shieh, C. H.
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p. 2499 - 2502
(2007/10/02)
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