62170-41-6Relevant academic research and scientific papers
Stereoselective Total Syntheses of Polyacetylene Plant Metabolites via Ester-Tethered Ring Closing Metathesis
Schmidt, Bernd,Aud?rsch, Stephan
, p. 1743 - 1760 (2017/02/10)
Total syntheses of five naturally occurring polyacetylenes from three different plants are described. These natural products have in common an E,Z-configured conjugated diene linked to a di- or triyne chain. As the key method to stereoselectively establis
Cobalt-catalyzed hydrohydrazination of dienes and enynes: Access to allylic and propargylic hydrazides
Waser, Jerome,Gonzalez-Gomez, Jose C.,Nambu, Hisanori,Huber, Pascal,Carreira, Erick M.
, p. 4249 - 4252 (2007/10/03)
(Chemical Equation Presented) The cobalt-catalyzed hydrohydrazination reaction of dienes and enynes is presented. Allylic and propargylic hydrazines were obtained in synthetically useful yields (allylic amines, 60-90%; propargylic amines, 47-83%) and good chemo- and regioselectivity.
Total synthesis and biological evaluation of the protein phosphatase 2A inhibitor cytostatin and analogues
Bialy, Laurent,Waldmann, Herbert
, p. 2759 - 2780 (2007/10/03)
The total synthesis of the natural product cytostatin is described which inhibits protein phosphatase 2A. Cytostatin has anti-metastatic properties and induces apoptosis. On the basis of this synthesis the relative and absolute configuration of cytostatin could be assigned. Key structural elements of cytostatin are an α,β-unsaturated lactone group and a side chain embodying a phosphate and a rather unstable (Z,Z,E)-triene subunit. In addition, the natural product carries six stereocenters. For the construction of the stereocenters reagent-controlled transformations were used in order to ensure maximum stereochemical flexibility. The Evans syn-aldol reaction was chosen to establish the stereochemistry at C-4, C-5, C-9 and C-10; C-6 was introduced by means of the Evans asymmetric alkylation. In all cases the same chiral auxiliary was employed as stereodirecting group. The stereocenter at C-11 was established by an asymmetric reduction using CBS-oxazaborolidine. Temporary protection of the phosphate group was achieved best by using the base-labile 9-fluorenylmethyl group, which could be cleanly cleaved by an excess of triethylamine; this reaction yielded analytically pure phosphates after a simple aqueous work-up. The (Z,Z,E)-triene embodied in cytostatin was synthesized by means of a Stille coupling as key transformation. The synthesis sequence established in this way readily gave access to a series of analogues with simplified structure. Initial biological testing of these analogues proved that the α,β-unsaturated lactone, the C-11-hydroxy group and a fully deprotected phosphate moiety at C-9 are essential for the PP2A-inhibitory activity of cytostatin. The rather unstable triene moiety in the side chain can be replaced by other lipophilic residues with only moderate decrease of biological activity. Other phosphatases, that is, PP1, VHR, PTP1B, CD45, were not inhibited by cytostatin or any of the analogues, demonstrating the high selectivity of this compound. These findings will be useful for the design and synthesis of cytostatin-derived chemical tools for the study of biological processes influenced by PP2A.
A novel, selective, and efficient route to carotenoids and related natural products via Zr-catalyzed carboalumination and Pd- and Zn-catalyzed cross coupling.
Zeng,Negishi
, p. 719 - 722 (2007/10/03)
[structure: see text]. A highly efficient and stereoselective protocol for the syntheses of symmetrical and unsymmetrical carotenoids involving Zr-catalyzed carboalumination of conjugated oligoenynes and Pd- and Zn-catalyzed alkenyl-alkenyl coupling has been developed and applied to the syntheses of beta- and gamma-carotene and vitamin A. gamma-Carotene of > or =99% isomeric purity was prepared in three linear steps (five steps overall) from beta-ionone, enyne 8, (E)-ICH=CHBr, and (E)-Me3SiC triple bond CCH=CHBr in 32% overall yield.
A convenient one-pot synthesis of (E)-silylated conjugated enynes from 1,1-bis(trimethylsilyl)-2-propyne and carbonyl derivatives
Pornet, Jacques,Princet, Bruno,Mevaa, Luc Mbaze,Miginiac, Leone
, p. 2099 - 2111 (2007/10/03)
1,1-Bis(trimethylsilyl)-2-propyne, prepared from propargyltrimethylsilane, was reacted, in the presence of a Lewis acid, with electrophiles (aldehydes, acetals) to afford (E)-silylated conjugated enynes.
