Studies on the Eschenmoser coupling reaction and insights on its mechanism. Application in the synthesis of Norallosedamine and other alkaloids
摘要:
The conditions of the Eschenmoser coupling reaction were studied. The formation of the alpha-thioiminium ion was achieved faster in the presence of an additive (Nal) and dry chloroform as the preferred solvent. The developed conditions were used for the second part of the reaction (the sulfur extrusion itself). The present protocol avoids the formation of byproducts, which were previously described as a major drawback to be overcome. Electrospray ionization tandem mass spectrometry was used to characterize some aspects (intermediates) of the first step of the reaction mechanism. Some reduction conditions were properly tested and the selected conditions were applied to the synthesis of the natural alkaloid Norallosedamine and other derivatives. (C) 2009 Elsevier Ltd. All rights reserved.
Ti(IV) promoted 1, 3-dipolar cycloaddition of nitrones to vinyl ethers
作者:Pau Bayo´n、Pedro de March、Marta Figueredo、Josep Font
DOI:10.1016/s0040-4020(98)00983-1
日期:1998.12
The 1, 3-dipolar cycloaddition of nitrones to vinylethers is accelerated by Ti(IV) species. The efficiency of the catalyst parallels its complexation capacity. The use of Ti(iPrO)2Cl2 favours the formation of trans cycloadducts, presumably through an endo bidentate complex, in which the metal atom is simultaneously coordinated to the vinylether and to the cyclic nitrone or the Z isomer of the acyclic
The present invention relates to pyrazolopyridines and imidazopyridines which are inhibitors of the kinase PDK1 and are thus useful for the treatment of myeloproliferative disorders or cancer. The compounds are also useful as inhibitors of other kinases such as FGFR3, NTRK3, RP-S6K and WEE1. Furthermore, the present compounds also selectively inhibit microtubule affinity regulating kinase (MARK) and are therefore useful for the treatment or prevention of Alzheimer's disease.
The present invention relates to pyrazolopyridines and imidazopyridines which are inhibitors of the kinase PDK1 and are thus useful for the treatment of myeloproliferative disorders or cancer. The compounds are also useful as inhibitors of other kinases such as FGFR3, NTRK3, RP-S6K and WEE1. Furthermore, the present compounds also selectively inhibit microtubule affinity regulating kinase (MARK) and are therefore useful for the treatment or prevention of Alzheimer's disease.
Tandem SN2-Michael reactions for the preparation of simple five- and six-membered-ring nitrogen and sulfur heterocycles
作者:Richard A. Bunce、Christopher J. Peeples、Paul B. Jones
DOI:10.1021/jo00032a025
日期:1992.3
A one-pot tandem S(N)2-Michael addition sequence has been developed for the preparation of five-membered- and six-membered-ring nitrogen and sulfur heterocycles from 6- or 7-halo-2-alkenoate esters. Nitrogen-containing rings are prepared by reaction of the omega-halo-2-alkenoate ester with a primary amine in the presence of triethylamine. The sulfur analogues are generated by thiourea displacement of the halide followed by base hydrolysis of the isothiouronium salt. Yields are routinely in the 60-80% range. Experiments are described which elucidate the chronology of the reaction sequences. Ring size and steric hindrance to the initial substitution reaction appear to be the only limitations of the procedure.
Doyle et al., Journal of the Chemical Society, 1958, p. 4458,4462