Petros Mamos

Simple fragment syntheses of all four isomers of the spermine alkaloid kukoamine

Abstract All four isomers of the spermine alkaloid kukoamine were unambiguously prepared through diacylation with O,O′ -dibenzylcaffeyl chloride of suitably protected (benzyl and/or trityl groups) spermine derivatives, assembled on solid and/or in liquid phase using β-alanine and γ-aminobutyric acid, followed by simultaneous N- and O- deprotection and double bond reduction using catalytic hydrogenation.

Simple total syntheses of N-substituted polyamine derivatives using N-tritylamino acids

Abstract A general methodology for the total synthesis of N -alkyl- and acylpolyamine derivatives is described which is based on the coupling of suitable N -tritylamino acids with amines followed by lithium aluminium hydride reduction of the thus obtained amides.

Simple syntheses of N-alkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A

Abstract Acylation of a variety of amines with succinimidyl N -trityl-β-alanyl-γ-aminobutyrate and N -trityl-γ-aminobutyryl-β-alaninate, readily obtained through coupling of succinimidyl N -trityl-β-alaninate with trimethylsilyl γ-aminobutyrate and of N -trityl-γ-aminobutyric acid with methyl β-alaninate, respectively, followed by LiAlH 4 reduction, produced N -monoalkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A. The applicability of this methodology on the solid phase was also demonstrated.

On the use of the antibiotic chloramphenicol to target polypeptide chain mimics to the ribosomal exit tunnel

The ribosomal exit tunnel had recently become the centre of many functional and structural studies. Accumulated evidence indicates that the tunnel is not simply a passive conduit for the nascent chain, but a rather functionally important compartment where nascent peptide sequences can interact with the ribosome to signal translation to slow down or even stop. To explore further this interaction, we have synthesized short peptides attached to the amino group of a chloramphenicol (CAM) base, such that when bound to the ribosome these compounds mimic a nascent peptidyl-tRNA chain bound to the A-site of the peptidyltransferase center (PTC). Here we show that these CAM-peptides interact with the PTC of the ribosome while their effectiveness can be modulated by the sequence of the peptide, suggesting a direct interaction of the peptide with the ribosomal tunnel. Indeed, chemical footprinting in the presence of CAM-P2, one of the tested CAM-peptides, reveals protection of 23S rRNA nucleotides located deep within the tunnel, indicating a potential interaction with specific components of the ribosomal tunnel. Collectively, our findings suggest that the CAM-based peptide derivatives will be useful tools for targeting polypeptide chain mimics to the ribosomal tunnel, allowing their conformation and interaction with the ribosomal tunnel to be explored using further biochemical and structural methods.

Simple syntheses of the polyamine alkaloid tenuilobine and analogues using selectively N-tritylated polyamines and dicarboxylic acids as bridging elements

Selectively N-tritylated spermidine and spermine derivatives and the monophenacyl ester of 1,16-hexadecanedioic acid (Hda) were used to obtain the polyamine alkaloid tenuilobine and its fully reduced analogue. Other symmetric or side-chain-shortened tenuilobine analogues were readily obtained by using Hda or its dichloride or succinic anhydride to bridge the polyamine moieties.

(S)-N-Triphenylmethylpyroglutamyl Fluoride

The title compound, C 24 H 20 FNO 2 , is the product of the reaction of (S)-N-triphenylmethylpyroglutamic acid with cyanuric fluoride in the presence of pyridine. The crystal structure determination shows the presence of two crystallographically independent molecules, with the two pyrrolidinyl rings adopting slightly different conformations.

Simple syntheses of (S)-2- and 4-amino-5-hydroxypentanoic acids

The title compounds were efficiently prepared by selective reductions of α- and γ-methyl (S)-N-tritylglutamates with LiAlH4

Synthesis and chemical modification of homoseryl peptides

The readily synthesised N,O-ditritylhomoserine (4) was used for the efficient incorporation of homoserine (1) into peptides; the derived homoseryl peptides were transformed into peptides of canaline and 1,4-diaminobutyric acid using the Mitsunobu reaction.