96293-26-4Relevant academic research and scientific papers
Electroreductive Cyclization. Ketones and Aldehydes Tethered to α,β-Unsaturated Esters (Nitriles). Fundamental Investigations
Little, R. Daniel,Fox, Dennis P.,Hijfte, Luc Van,Dannecker, Robert,Sowell, Gregory,et al.
, p. 2287 - 2294 (1988)
The intramolecular electrochemically initiated cyclization of a variety of α,β-unsaturated esters and one nitrile, each of which is tethered to an aldehyde or a ketone, has been investigated.Good yields (70-79percent) of mono- and bicyclic products, resulting from closure between the β-carbon of the α,β-unsaturated unit and the aldehyde or ketone carbonyl carbon, were obtained.Cyclic voltammetry was used to determine that the α,β-unsaturated unit corresponded to the electrophore.In all but one instance, cyclization favored formation of the product wherein the hydroxy and (methoxycarbonyl)methyl units were trans to one another.The stereoselectivity was studied as a function of temperature, nature of the proton donor, proton availability, and percent conversion (i.e., as a function of time).Attempts to use the reaction to synthesize the marine natural product ambliol A were unsuccessful.A mechanistic scheme in which a reversible cyclization of the initially formed radical anion is followed by an irreversible proton transfer is suggested to account for the experimental observations.
X = Y - ZH systems as potential 1,3-dipoles part 35. Generation of nitrones from oximes. Class 3 processes. Tandem intramolecular Michael addition (1,3-azaprotio cyclotransfer) - Intermolecular 1,3-dipolar cycloaddition reactions
Grigg, Ronald,Markandu, Jasothara,Perrior, Trevor,Surendrakumar, Sivagnanasundram,Warnock, William J.
, p. 6929 - 6952 (2007/10/02)
Aldoximes and ketoximes possessing γ- or δ-alkenyl substituents undergo thermal conversion to 5-and 6- membered cyclic nitrones via a 1,3-azaprotio cyclotransfer, a 2n + 2oσ + 2π concerted process, rather than a Michael addition. The reactions can be performed as a tandem nitrone formation-cycloaddition sequence or, if required, the intermediate nitrones can be isolated. The cycloadditions usually proceed via an exo-transition state and show both regio- and diastereofacial-specificity. Preliminary attempts at chiral induction via a menthyl auxiliary are reported.
