Stereoselective synthesis of C-alkyl and functionalised C-alkyl glycosides using ‘thiophene’ as a masked C-4 synthon

Krishna, Palakodety Radha; Lavanya, B.; Ilangovan, A.; Sharma, G. V. M.

doi:10.1016/s0957-4166(00)00423-7

Cited by 22 publications

(12 citation statements)

References 17 publications

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“…Guerrieri et al 2463 group in the 11-position of the final product. Previously, thiophenes have been used successfully within other research areas as 4-carbon synthons (Krishna et al 2000;Mohr et al 2005). Also, Pomonis et al (1989) prepared related hydrocarbons from thiophenes, although with a different set of subreactions than presented here.…”

Section: Methodsmentioning

confidence: 99%

Ants recognize foes and not friends

et al. 2009

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Discriminating among individuals and rejecting non-group members is essential for the evolution and stability of animal societies. Ants are good models for studying recognition mechanisms, because they are typically very efficient in discriminating 'friends' (nest-mates) from 'foes' (non-nest-mates). Recognition in ants involves multicomponent cues encoded in cuticular hydrocarbon profiles. Here, we tested whether workers of the carpenter ant Camponotus herculeanus use the presence and/or absence of cuticular hydrocarbons to discriminate between nest-mates and non-nest-mates. We supplemented the cuticular profile with synthetic hydrocarbons mixed to liquid food and then assessed behavioural responses using two different bioassays. Our results show that (i) the presence, but not the absence, of an additional hydrocarbon elicited aggression and that (ii) among the three classes of hydrocarbons tested (unbranched, mono-methylated and dimethylated alkanes; for mono-methylated alkanes, we present a new synthetic pathway), only the dimethylated alkane was effective in eliciting aggression. Our results suggest that carpenter ants use a fundamentally different mechanism for nest-mate recognition than previously thought. They do not specifically recognize nest-mates, but rather recognize and reject non-nest-mates bearing odour cues that are novel to their own colony cuticular hydrocarbon profile. This begs for a reappraisal of the mechanisms underlying recognition systems in social insects.

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Section: Methodsmentioning

confidence: 99%

Ants recognize foes and not friends

et al. 2009

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“…Only rare reports of the reduction of as ubstitutedv inylthiophene into the corresponding n-hexyl fragment were found. [54] The substituted ethynylthiophene anti-21 Ca,s elected as am odel substrate, was subjected to Raney-Ni, ac ommonr eagent for reductive desulfurization. [55] Ethynylthiophene (1 mmol) was treated with activated Raney-Ni (5 wt equiv) in anhydrous methanol( 4mL) under 1atmosphere of hydrogen.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, to our knowledge, no precedent for such a reductive process, combining the hydrogenation of an alkyne unit and the HDS of a thiophene ring, has so far been described in literature. Only rare reports of the reduction of a substituted vinylthiophene into the corresponding n ‐hexyl fragment were found …”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis and Binding Study of New Long‐Chain HPA‐12 Analogues as Potent Ligands of the Ceramide Transfer Protein CERT

Ďuriš

Daı̈ch

Santos

et al. 2016

Chemistry A European J

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A series of 12 analogues of the Cer transfer protein (CERT) antagonist HPA-12 with long aliphatic chains were prepared as their (1R,3S)-syn and (1R,3R)-anti stereoisomers from pivotal chiral oxoamino acids. The enantioselective access to these intermediates as well as their ensuing transformation relied on a practical crystallization-induced asymmetric transformation (CIAT) process. Sonogashira coupling followed by triple bond reduction and thiophene ring hydrodesulfurization (HDS) into the corresponding alkane moieties was then implemented to complete the synthetic routes delivering the targeted HPA-12 analogues in concise 4- to 6-step reaction sequences. Ten compounds were evaluated regarding their ability to bind to the CERT START domain by using the recently developed time-resolved FRET-based homogeneous (HTR-FRET) binding assay. The introduction of a lipophilic appendage on the phenyl moiety led to an overall 10- to 1000-fold enhancement of the protein binding, with the highest effect being observed for a n-hexyl residue in the meta position. The importance of the phenyl ring for the activity was indicated by the reduced potency of the 3-deoxyphytoceramide aliphatic analogues. The 1,3-syn stereoisomers were systematically more potent than their 1,3-anti analogues. In silico studies were used to rationalized these trends, leading to a model of protein recognition coherent with the stronger binding of (1R,3S)-syn HPAs.

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“…The fragment 5 was proposed to be accessed from a C-alkyl glycoside 6 by employing an appropriately substituted thiophene as a masked C4-synthon. 9 We visualized that n-propylthiophene could serve as a surrogate for the n-heptyl appendage present in the target molecule after reductive desulfurization of the thiophene nucleus. The other alkyne fragment 4 was proposed to be accessed by an enzymatic kinetic resolution/Mitsunobu inversion sequence or Trost asymmetric alkynylation protocol 10 as shown in Scheme 1.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 98%