synthons in organic synthesis. This involves a photoactivated multicomponent reaction, performed both in batch and under continuous flow conditions. This process affords the desired compounds in a stereoselective fashion from readily available starting materials in one step, without the aid of metal catalysis. This paper illustrates the preliminary work, the extensive experiments carried out to understand
Toward a Green Atom Economy: Development of a Sustainable Multicomponent Reaction
作者:Stefano Protti、Andrea Basso、Silvia Garbarino
DOI:10.1055/s-0034-1380719
日期:——
discovered photoinduced three-component reaction of diazo ketones, carboxylic acids, and isocyanides can be efficiently performed under continuous-flow conditions with consequential advantages in terms of selectivity and productivity. The investigation of the flow process and the determination of its sustainability are discussed in detail. This multicomponent reaction affords stereodefined captodative olefins
Alkylation of benzene with α-diazoketones via cycloheptatrienyl intermediates
作者:M. Anthony McKervey、D. Noel Russell、M. Fiona Twohig
DOI:10.1039/c39850000491
日期:——
Benzyl ketones can be synthesised efficiently from benzene and α-diazoketones with sequential catalysis by rhodium(II) trifluoroacetate and trifluoroacetic acids; the process involves cycloheptatrienylintermediates.
Oxazole activation for azomethine ylide trapping: singly and doubly tethered substrates
作者:Edwin Vedejs、David W. Piotrowski
DOI:10.1021/jo00058a010
日期:1993.3
Bicyclic oxazolium salts 18, 24, 37, and 44 can be generated from tethered haloalkyloxazoles by internal alkylation. Reductive alkylation of the oxazolium salts using CsF/PhSiH3 converts the salts initially into the corresponding 4-oxazoline derivatives. Subsequent electrocyclic ring opening generates stabilized azomethine ylides that can be trapped by suitable dipolarophiles. Intermolecular dipole trapping followed by DDQ oxidation affords the ring-fused pyrroles 22 and 26. When tethered alkynoates are used for internal dipole trapping, the adducts 38 and 45 can be obtained by a similar reductive activation sequence, followed by DDQ workup. Effective procedures for the internal oxazole N-alkylation step are described using an acetonitrile-trifluoroethanol solvent system. Also, an improved method for the generation of the dichlorocerium derivative of ethyl propiolate and intermolecular trapping by an aldehyde is reported.