Rh<sub>2</sub>(<i>R</i>-TPCP)<sub>4</sub>-Catalyzed Enantioselective [3+2]-Cycloaddition between Nitrones and Vinyldiazoacetates
作者:Changming Qin、Huw M. L. Davies
DOI:10.1021/ja4069003
日期:2013.10.2
Rhodium-catalyzed reaction of vinyldiazoacetates with nitrones results in a formal [3+2]-cycloaddition to generate 2,5-dihydroisoxazoles with high levels of asymmetricinduction. The cascade reaction begins with a vinylogous addition event, followed by an iminium addition ring-closure/hydride migration/alkene isomerization cascade. Dirhodium tetrakis(triarylcyclopropanecarboxylates) are the optimum
Allyl esters substituted by a difluoromethylene group, their process of synthesis and their use, and a process for functionalizing a double bond
申请人:RHODIA CHIMIE
公开号:US20040147789A1
公开(公告)日:2004-07-29
This invention provides compounds of formula:
1
in which R
f
is a radical that carries a perfluoromethylene group, which group ensures bonding to the remainder of the molecule; R1 and R3, which can be the same or different, are chosen from among hydrogen and alkyl or aryl radicals; &PSgr; is an electroattractor group such that &PSgr;-O—H is an acid whose pKa (in water) is at most equal to 8, advantageously 6, and preferably 5. These compounds are useful for the synthesis of nitrogen-containing heterocyclic compounds.
1,3-Dipolar cycloadditions to 5-methoxy-2(5H)-furanone
作者:Erik Keller、Ben de Lange、Minze T. Rispens、Ben L. Feringa
DOI:10.1016/s0040-4020(01)81909-8
日期:1993.1
Various nitrile oxides and nitrones, ethyl diazoacetate and an azomethine ylide were examined in 1,3-dipolarcycloadditions to 5-methoxy-2[5H]-furanone, in particular with respect to regio- and diastereoselectivities. Isoxazoles 13–17 and isoxazolidines 21, 22 and 24 were obtained in high yields with anti-facial selectivities and regioselectivities exceeding 95%. In the case of pyrazoline 26 minor
palladium-catalysed four-component process is described involving carbon monoxide, allene and aryl/heteroaryl iodides generating (π-allyl) palladium species, which are intercepted by alkene tethered nitrogen nucleophiles to afford 1,6- and 1,7-dienones. Subsequent ring closing metathesis affords five- and six-membered N-heterocyclic enones. The N-heterocyclic enones are active dipolarophiles in 1,3-dipolar
New Bicyclic Conjugates of Three- and Five-Membered Heterocycles with 5-Alkoxyfuran-2(5H)-ones (4-Alkoxy-Δ2-butenolides)
作者:H. M. R. Hoffmann、K. Gerlach、E. Lattmann
DOI:10.1055/s-1996-4157
日期:1996.1
The title molecules were built up by 1,3-dipolar cycloaddition and by palladium-catalyzed cross coupling of 4-bromofuran-2(5H)-ones with heterocyclic stannanes.