Total synthesis of (+)-kalkitoxinElectronic supplementary information (ESI) available: experimental procedures and spectroscopic data. See http://www.rsc.org/suppdata/cc/b3/b306124h/
Total synthesis and biological evaluation of (+)-kalkitoxin, a cytotoxic metabolite of the cyanobacterium Lyngbya majusculaElectronic supplementary information (ESI) available: 1H NMR spectrum of synthetic (+)-kalkitoxin in C6D6. See http://www.rsc.org/suppdata/ob/b4/b404205k/
作者:James D. White、Qing Xu、Chang-Sun Lee、Frederick A. Valeriote
DOI:10.1039/b404205k
日期:——
+-Kalkitoxin, a metabolite of the marine cyanobacteriumLyngbyamajuscula, was synthesized from (R)-2-methylbutyric acid, (R)-cysteine, and (3S, 4S, 6S)-3,4,6-trimethyl-8-(methylamino)octanoic acid. A key step in the synthesis was installation of the anti,anti methyl stereotriad by means of a tandem asymmetric conjugate addition of an organocopper species to an alpha,beta-unsaturated N-acyl oxazolidin-2-one
An expeditious total synthesis of kalkitoxins: determination of the absolute stereostructure of natural kalkitoxin
作者:Fumiaki Yokokawa、Toshinobu Asano、Tatsufumi Okino、William H. Gerwick、Takayuki Shioiri
DOI:10.1016/j.tet.2004.06.014
日期:2004.8
Kalkitoxin, a potent neurotoxin isolated from the marine cyanobacteria Lyngbyamajuscula, and its congeners (1–7) were efficiently synthesized utilizing Hruby's diastereoselective 1,4-addition and the Wipf's oxazoline-thiazoline conversion as key steps. These synthetic efforts in combination with spectral studies of natural kalkitoxin clearly determined the absolute stereostructure of kalkitoxin to
Toward Ideality: The Synthesis of (+)-Kalkitoxin and (+)-Hydroxyphthioceranic Acid by Assembly-Line Synthesis
作者:Sebastien Balieu、Gayle E. Hallett、Matthew Burns、Teerawut Bootwicha、John Studley、Varinder K. Aggarwal
DOI:10.1021/ja512875g
日期:2015.4.8
The iterative homologation of boronic esters using chiral lithiated benzoate esters and chloromethyllithium has been applied to the highly efficient syntheses of two natural products, (+)-kalkitoxin and (+)-hydroxyphthioceranic acid. The chiral lithiated benzoate esters (>99% ee) were generated from the corresponding stannanes, which themselves were prepared by HoppeBeak deprotonation of ethyl 2,4,6-triisopropyl-benzoate with s-BuLi in the presence of (+)- or (-)-sparteine and trapping with Me3SnCl followed by recrystallization. In addition, it was found that purification between several homologations could be avoided, substantially increasing both chemical and manpower efficiency. In the case of (+)-kalkitoxin, six iterative homologations were conducted on commercially available p-MeOC(6)H(4)CH(2)Bpin to build up the core of the molecule before the C-B bond was converted into the desired CN bond, without purification of intermediates. In the case of (+)-hydroxyphthioceranic acid, 16 iterative homologations were conducted on p-MeOC(6)H(4)Bpin with only four intermediate purifications before oxidation of the C-B bond to the desired alcohol. The stereocontrolled and efficient syntheses of these complex molecules highlight the power of iterative chemical synthesis using boronic esters.
Synthesis and Biological Activity of Kalkitoxin and its Analogues
Total syntheses of kalkitoxin, isolated from the Caribbean Lyngbya majuscula, and its analogues, 3-epi-, 7-epi-, 8-epi-, 10-epi-, 10-nor-, and 16-nor-kalldtcocin, were achieved via oxazolidinone-based diastereoselective 1,4-addition reaction of a methyl group and efficient T1C14-mediated thiazoline ring formation as the key steps. The biological activities of synthetic kalkitoxin and its analogues were evaluated with brine shrimp.
Structure, Synthesis, and Biological Properties of Kalkitoxin, a Novel Neurotoxin from the Marine Cyanobacterium <i>Lyngbya </i><i>m</i><i>ajuscula</i>
作者:Min Wu、Tatsufumi Okino、Lisa M. Nogle、Brian L. Marquez、R. Thomas Williamson、Namthip Sitachitta、Frederick W. Berman、Thomas F. Murray、Kevin McGough、Robert Jacobs、Kimberly Colsen、Toshinobu Asano、Fumiaki Yokokawa、Takayuki Shioiri、William H. Gerwick