Partner und Internationale Organisationen
(Englisch)
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A, B, HR, CZ, DK, F, D, H, IRL, I, LV, NL, N, PL, P, RO, SI, E, S, CH, GB
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Abstract
(Englisch)
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1. TRANSITION METAL-CATALYZED DECOMPOSITION OF PHENYLIODONIUM YLIDESThe decomposition of phenylidonium ylides by transition metal-catalysts based on Rh(II) or Cu(I) affords metal carbenoids capable of asymmetric carbene transfer. It was shown that CH insertions in the presence of both both Rh(II)- and Cu(I)-catalysts the reaction proceeds with retention of configuration at the carbon atom undergoing insertion. Cu(I)-catalyzed asymmetric intramolecular CH insertions using phenyliodonium ylides have been realized with up to 72% enantiomeric excess. Conditions allowing in situ generation and decomposition of the phenyliodonium ylide derived from Meldrum's acid have been developed. 2. ENANTIOSELECTIVE CYCLOPROPANATIONS WITH TRIFLUOROMETHYL SUBSTITUTED DIAZOACETATESThe Rh(II)-catalyzed asymmetric cyclopropanation of olefins with ethyl 3,3,3-trifluoro-2-diazopropionate has been investigated with chiral Rh(II)-catalysts. The reaction proceeds with good yields to afford mixtures of cis and trans-cyclopropanes. However, at present, the enantioselectivity iof the reaction is modest.s modest. 3. INTRAMOLECULAR CH INSERTION OF ALKYL DIAZO(TRIETHYLSILYL)ACETATESConditions were found under which the Rh(II)-catalyzed intramolecular insertion of silylated diazoacetate esters proceeds in high yields at room temperature. Enantioselectivities of up to 79% have been achieved. 4. INTERMOLECULAR CYCLOPROPANATION WITH A VINYLDIAZOACETATE ESTERThe intermolecular cyclopropanation of 2,3-dihydrofuran and styrene with silylated enolethers derived from diazoacetate esters is fully stereoselective. It proceeds with enantioselectivities of >90% with a newly designed Rh(II)-catalysts. The cyclopropanes may be converted to synthetically useful intermediates.
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