213026-20-1Relevant articles and documents
Total synthesis and biological evaluation of the nakijiquinones
Stahl,Kissau,Mazitschek,Huwe,Furet,Giannis,Waldmann
, p. 11586 - 11593 (2007/10/03)
The Her-2/Neu receptor tyrosine kinase is vastly overexpressed in about 30% of primary breast, ovary, and gastric carcinomas. The nakijiquinones are the only naturally occurring inhibitors of this important oncogene, and structural analogues of the nakijiquinones may display inhibitory properties toward other receptor tyrosine kinases involved in cell signaling and proliferation. Here, we describe the first enantioselective synthesis of the nakijiquinones. Key elements of the synthesis are (i) the reductive alkylation of a Wieland - Mieschertype enone with a tetramethoxyaryl bromide, (ii) the oxidative conversion of the aryl ring into a p-quinoid system, (iii) the regioselective saponification of one of the two vinylogous esters incorporated therein, and (iv) the selective introduction of different amino acids via nucleophilic conversion of the remaining vinylogous ester into the corresponding vinylogous amide. The correct stereochemistry and substitution patterns are completed by conversion of two keto groups into a methyl group and an endocyclic olefin via olefination/reduction and olefination/isomerization sequences, respectively. This synthesis route also gave access to analogues of nakijiquinone C with inverted configuration at C-2 or with an exocyclic instead of an endocyclic double bond. Investigation of the kinase-inhibiting properties of the synthesized derivatives revealed that the C-2 epimer 30 of nakijiquinone C is a potent and selective inhibitor of the KDR receptor, a receptor tyrosine kinase involved in tumor angiogenesis. Molecular modeling studies based on the crystal structure of KDR and a model of the ATP binding site built from a crystal structure of FGF-R revealed an insight into the structural basis for the difference in activity between the natural product nakijiquinone C and the C-2 epimer 30.
Efficient total synthesis of (-)-ilimaquinone
Poigny, Stephane,Guyot, Michele,Samedi, Mohammad
, p. 5890 - 5894 (2007/10/03)
The total synthesis of (-)-ilimaquinone, a metabolite isolated from sea sponges, is described. The key step of the synthesis is the attachment of the quinone moiety to the drimane skeleton. Alkylation of enone 11 obtained in four steps from the readily available diketone 8, with tetramethoxybenzyl bromide 15 as the alkylating agent, led to addition product 16 in excellent yield. The presence of the tetramethoxybenzyl group induced stereoselective hydrogenation of the exo olefin 18, leading to the required isomer in a 9:1 ratio. Treatment of compound 21 with ceric ammonium nitrate (CAN) afforded formation of the quinone and deprotection of only one methyl ether in one step to furnish the desired ilimaquinone 1.