120113-93-1Relevant articles and documents
The influence of α-coordinating groups of aldehydes on E/Z-selectivity and the use of quaternary ammonium counter ions for enhanced E-selectivity in the Julia–Kocienski reaction
Rehman, Mintu,Surendran, Sravya,Siddavatam, Nagendra,Rajendar, Goreti
supporting information, p. 329 - 333 (2022/01/20)
Modified reaction conditions for improved E-selectivity of olefins in the Julia–Kocienski reaction of aldehydes having α-coordinating substituents are demonstrated. The chelating groups in aldehydes are expected to stabilize the syn-transition state with metal ions, whereas the weakly coordinating quaternary ammonium ions are devoid of all possible chelating interactions to enhance E-selectivity. A systematic investigation is presented to study the size of the neighbouring protecting groups of aldehydes and their chelation effect on E/Z-selectivity in the Julia–Kocienski reaction.
Synthesis of 2,5-dihydrofurans via alkylidene carbene insertion reactions
Walker, Louise F.,Bourghida, Ahmed,Connolly, Stephen,Wills, Martin
, p. 965 - 981 (2007/10/03)
The insertion reaction of alkylidene carbenes is demonstrated to be an effective method for the synthesis of 2,5-dihydrofuran ring systems. The best results have been obtained on substrates containing electron-withdrawing substituents, which appear less prone to the competing rearrangement reaction. This insight has led to the development of a new method for the synthesis of the core structure of the squalestatin-zaragozic acid natural products.
Acyclic stereoselection in the tertiary amine-catalysed addition of activated vinyl systems (Baylis-Hillman reaction) to protected chiral α-hydroxy and α-amino aldehydes
Manickum, Thavrin,Ross, Gregory H. P.
, p. 1 - 16 (2007/10/03)
The non chelation-controlled aldol-type addition of the ambident vinyl α anions derived from acrylic esters and methyl vinyl ketone to a series of protected chiral α-hydroxy and α-amino aldehydes has been investigated in order to assess some of the factors which contribute to the control of the diastereofacial selectivity.Whlist the α-methylene-β,γ-disubstituted carbonyl products showed a general preference for selectivity, some examples of syn predominance were made possible via a 'substituent tuning'approach.The observed diastereomer ratios have been interpreted in terms of the Felkin model and the Anh-Eisenstein proposals for 1,2-asymmetric induction.Simple steric effects appear to be as important as ?-orbital energies in the designation of the large 'anti group' for the application of these transition-state interpretations.Attempts to improve the overall induction via double diastereoselection approach, which combines the 1,5-induction of chiral acrylates with the 1,2-induction already present, were largely inconclusive.Methods for the routine NMR assignment of the relevant stereo-substructures have been assessed and the use of novel complementary technique is described.