Improvement on the synthesis of (E )-alk-3-enoic acids

Ragoussis, Nikitas; Ragoussis, Valentine

doi:10.1039/a806173d

Cited by 41 publications

(28 citation statements)

References 22 publications

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“…The synthesis of the para -trifluoromethyl substituted unit A started with a modified Knoevenagel condensation [23,31]. The required aldehyde 9 was obtained by DIBAL-H reduction of the corresponding methyl ester 8 and was found to decompose upon chromatographic purification (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Total synthesis and biological evaluation of fluorinated cryptophycins

Weiß¹,

Bogner²,

Sammet³

et al. 2012

Beilstein J. Org. Chem.

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SummaryCryptophycins are cytotoxic natural products that exhibit considerable activities even against multi-drug-resistant tumor cell lines. As fluorinated pharmaceuticals have become more and more important during the past decades, fluorine-functionalized cryptophycins were synthesized and evaluated in cell-based cytotoxicity assays. The unit A trifluoromethyl-modified cryptophycin proved to be highly active against KB-3-1 cells and exhibited an IC50 value in the low picomolar range. However, the replacement of the 3-chloro-4-methoxyphenyl-substituent in unit B by a pentafluorophenyl moiety resulted in a significant loss of activity.

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Section: Resultsmentioning

confidence: 99%

Total synthesis and biological evaluation of fluorinated cryptophycins

Weiß¹,

Bogner²,

Sammet³

et al. 2012

Beilstein J. Org. Chem.

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“…The reaction proceeded in DMF (or DMSO) at 100 8C with piperidinium acetate (1-4 mol %) as the sole catalyst. [20] However, under these conditions, the substrate scope is limited. To overcome these limitations we were interested to identify milder reaction conditions, which would allow us to run the deconjugative and decarboxylative Knoevenagel reaction at lower temperatures.…”

Section: Resultsmentioning

confidence: 99%

Combined Transition‐Metal‐ and Organocatalysis: An Atom Economic C3 Homologation of Alkenes to Carbonyl and Carboxylic Compounds

Kemme

Šmejkal

Breit

2010

Chemistry A European J

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A combination of regioselective room-temperature/ambient-pressure hydroformylation (transition-metal catalysis) and decarboxylative Knoevenagel reactions (organocatalysis) allowed for the development of an efficient, one-pot C3 homologation of terminal alkenes to (E)-alpha,beta-unsaturated acids and esters, (E)-beta,gamma-unsaturated acids, (E)-alpha-cyano acrylic acids, and alpha,beta-unsaturated nitriles. All reactions proceed under mild conditions, tolerate a variety of functional groups, and furnish unsaturated carbonyl compounds in good yields and with excellent regio- and stereocontrol. Further, an iterative C2 homologation of (E)-alpha,beta-unsaturated carboxylic acids is possible through a combination of decarboxylative hydroformylation employing a supramolecular catalyst followed by decarboxylative Knoevenagel condensation with an organocatalyst.

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“…9 But the toxicity of carbon monoxide and the troublesome gas handling procedures limit the carbonylation processes for the high throughput chemistry involved in pharmaceutical industry. 10 Alternative ways include the deprotonation and reprotonation of (E)-β,γ-unsaturated esters, 11 Knoevenagel type reaction 12 and the reactions of ethyl α-bromoacetate or ethyl dimethylsulfuranylideneacetate with the air sensitive 9-alkenyl-9-BBN as the starting material.…”

Section: Introductionmentioning

confidence: 99%