216223-19-7Relevant academic research and scientific papers
Stereoselective Hydrocoupling of Optically Active 3-fraws-Cinnamoyloxazolidinones by Electroreduction
Kise, Naoki,Mashiba, Syun-Ichiro,Ueda, Nasuo
, p. 7931 - 7938 (1998)
Reductive hydrocoupling of chiral 3-trans-cinnamoyloxazolidinones was studied by an electrochemical method. The electroreduction was performed conveniently at a constant current using an undivided cell. The stereoselectivity of the hydrodimers was strongly affected by the electrolyte employed. Electroreduction of (S)-4-isobutyl-3-trais-cinnamoyloxazolidinone la in 0.3 M Et4NOTs/ AN gave a mixture of two diastereomers of all-trans cyclized hydrodimer 2a, and the selectivity was R,S,R/S,R,S = 85:15. On the other hand, the reduction of la in 1.7 M LiClO4/THF afforded a diastereomeric mixture of hydrodimers in a selectivity of R,R/S,S/R,S = 5:52:43. The stereoselectivities were explained by considering stable conformations of intermediate anion radicals, that is, syn-Z type for naked anion radicals and anti-Z type for lithiated anion radicals. Semiempirical calculations also supported this hypothesis. Electroreductions of (S)-4-isobutyl-3-c/s-cinnamoyloxazolidinone and (S)-4-isobutyl-3-phenylpropioloyloxazolidinone gave 2a in the same stereoselectivity as electroreduction of la did. The electroreductive hydrocoupling was not inhibited by para and meta substitution on the aryl group of 3-Zrans-cinnamoyloxazolidinones. An ortho substitution, however, hindered the hydrocoupling and lowered the stereoselectivity of the hydrodimers. Electroreduction of 3-trans-cinnamoyloxazolidinethione and thiazolidinethione gave trarcs-3,4-diphenylcyclopentanone as a product, and the stereoselectivities were similar to that obtained from the corresponding oxazolidinone.
Oxidatively initiated NHC-catalyzed enantioselective synthesis of 3,4-disubstituted cyclopentanones from enals
White, Nicholas A.,Rovis, Tomislav
supporting information, p. 10112 - 10115 (2015/09/01)
An unprecedented N-heterocyclic carbene (NHC)-catalyzed annulation of enals to form 3,4-disubstituted cyclopentanones has been discovered. Aryl enals undergo dimerization in the presence of a single-electron oxidant to form C2 symmetric cyclopentanones. A cross-reaction has also been developed, allowing for the synthesis of differentially substituted cyclopentanones. Mechanistically, the reaction is thought to proceed through radical intermediates, further establishing the synthetic utility of this class of reactivity.
