34839-17-3Relevant academic research and scientific papers
Application of chiral sulfides to catalytic asymmetric aziridination and cyclopropanation with in situ generation of the diazo compound
Aggarwal, Varinder K.,Alonso, Emma,Fang, Guangyu,Ferrara, Marco,Hynd, George,Porcelloni, Marina
, p. 1433 - 1436 (2001)
Imines and alkenes can be converted into the corresponding aziridines and cyclopropanes (see scheme, PTC = phase-transfer catalyst, Ts = toluene-4-sulfonyl) in good yield with moderate to high d.r. and high ee values using tosylhydrazone salts with catalytic quantities of chiral sulfide (5-20 mol%) and metal catalyst (1 mol%). The process is particularly suited to the synthesis of conformationally locked cyclopropyl amino acids, which can now be prepared in only three steps from commercially available material in 100% ee.
New synthesis and cyclopropanation of α-phenylselanyl α,β-unsaturated ketones with non-stabilized phosphorus ylides
Redon, Sébastien,Leleu, Stéphane,Pannecoucke, Xavier,Franck, Xavier,Outurquin, Francis
, p. 9293 - 9304 (2008/12/22)
A general method for the preparation of α-phenylselanyl enones is described. Phosphorus ylides react with these α-phenylselanyl enones in a 1,4-addition, leading to cyclopropanes and/or dihydrofurans, depending on the substitution pattern. This unusual reactivity is due to the phenylselanyl moiety, hindering the carbonyl of the enone and making it less prone to 1,2-additions or promoting conjugate addition by electronic effects.
Catalytic cyclopropanation of electron deficient alkenes mediated by chiral and achiral sulfides: Scope and limitations in reactions involving phenyldiazomethane and ethyl diazoacetate
Aggarwal, Varinder K.,Smitha, Helen W.,Hynd, George,Jones, Ray V.H.,Fieldhouse, Robin,Spey, Sharon E.
, p. 3267 - 3276 (2007/10/03)
Phenyldiazomethane reacts with electron deficient alkenes in the presence of catalytic amounts of transition metal catalyst [Rh2(OAc)4 was better than Cu(acac)2] and catalytic amounts of sulfide to give cyclopropanes. Pentamethylene sulfide was found to be superior to tetrahydrothiophene and the optimum solvent was toluene. Under these optimised conditions a range of enones were cyclopropanated in high yields. Cyclic enones and acrylates were not successful in this process. The use of the chiral 1,3-oxathiane derived from camphorsulfonyl chloride in 2 steps in this process furnished cyclopropanes in good yield and very high enantiomeric excess (>97% ee). The absolute stereochemistry of cyclopropane 10 was proven by X-ray analysis and the origin of the stereochemical induction has been rationalised. Extension of this work to include diazoesters was partially successful. Again pentamethylene sulfide was found to be superior to tetrahydrothiophene, but this time both Rh2(OAc)4 and Cu(acac)2 were found to be equally effective. Enones, fumarates and unsaturated nitro compounds worked well but simple acrylates and unsaturated aldehydes were not effective substrates. Control experiments were conducted in which the stabilised ylide was isolated and reacted with the less successful substrates and, whilst unsaturated aldehydes still gave low yields, simple acrylates gave high yields of the corresponding cyclopropane. The use of the chiral 1,3-oxathiane was not successful with these more stable diazo compounds.
Catalytic asymmetric cyclopropanation of electron deficient alkenes mediated by chiral sulfides
Aggarwal, Varinder K.,Smith, Helen W.,Jones, Ray V. H.,Fieldhouse, Robin
, p. 1785 - 1786 (2007/10/03)
Catalytic asymmetric cylopropanation of enones has been achieved using diazo compounds, catalytic quantities of a metal catalyst and a camphor-derived thioacetal; this sulfide shows exceptionally high levels of enantioselectivity.
