Electrospray ionization tandem mass spectrometry of 3-[4-bis-N,N-(2- chloroethyl)aminophenyl]acetates of estrane series.

Collision-induced fragmentation of the [M + Na]+ and [M + H]+ ions generated from 3-[4-bis-N,N-(2-chloroethyl)aminophenyl]acetates in the estrane series under electrospray/ionization was studied. Some regularities in fragmentation pathways depending on the nature of functional groups were established. Formation of the [(M + Na) NaCl]+ ions along with [(M + Na) HCl]+ ions from the [M + Na]+ ions was explained using quantum chemical calculations for some simplified models.

Letter: steric effects in electrospray-tandem mass spectrometry of 11betanitrates of estrane series.

The fragmentation of [M+Na](+) ions produced from steroid 11beta-nitrates during electrospray/ionization (ESI) was studied by using ion trap MS/MS technique. The [M+Na](+) ions eliminate NO(2) and HNO(3) for epimers bearing 9beta and 9alpha substituents, respectively. As the main fragmentation pathways are determined mainly by the configuration at C-9 and alternative fragmentation does not practically occur, this offers the possibility for the determination of the configuration at chiral C-9 centre in the estrane 11beta-nitrate series by ESI mass spectrometry.

[Synthetic studies in the series of polyene macrolide antibiotics. 4. Synthesis of methyl-2,4,6-trideoxy-3-0-benzoyl-2,4-di-C-methyl- alpha-L-talo-hexopyranoside and 2,4,6-trideoxy-2,4-di-C-methyl-L- galactitol, the stereoisomers of the fragment C33-C38 of amphotericin B]. / Sinteticheskie issledovaniia v riadu polienovykh makrolidnykh antibiotikov. 4. Sintez metil-2,4,6-tridezoksi-3-0-benzoil-2,4-di-C- metil-alpha-L-talo-geksopiranozida i 2,4,6-tridezoksi-2,4-di-C- metil-L-dul'tsita--stereoizomerov fragmenta C33-C38 amfoteritsina B.

Synthesis of methyl 2,4,6-trideoxy-3-O-benzoyl-2,4-di-C-methyl-alpha-L-talohexopyranoside and 2,4,6-trideoxy-2,4-di-C-methyl-L-galactitol, stereoisomers of the C33-C38 fragment of amphothericin B, is described.

[Synthetic studies in the series of polyene macrolide antibiotics. 6. Synthesis of methyl-2,4,6-trideoxy-2,4-dimethyl-alpha-altro- hexopyranoside, the C33-C38 fragment of amphotericin B]. / Sinteticheskie issledovaniia v riadu makrolidnykh antibiotikov. 6- Sintez metil-2,4,6-tridezoksi-2,4-dimetil-alpha-L-al'tro- geksopiranozida, fragmenta C33-C38 amfoteritsina B.

The synthesis of methyl 2,4,6-trideoxy-2,4-dimethyl-alpha-L-altro-hexopyranoside, having the configuration of the C33-C38 fragment of amphotericin B, is described.

[Synthetic studies in the series of polyene macrolide antibiotics. 5. Synthesis of methyl-2,4,6-trideoxy-2,4-di-C-methyl-alpha-L- gluco-hexopyranoside and methyl-2,4,6-trideoxy-2,4-di-C-methyl- alpha-L-manno-hexopyranoside, the stereoisomers of the C33-C38 fragment of amphotericin B]. / Sinteticheskie issledovaniia v riadu polienovykh makrolidnykh antibiotikov. 5. Sintez metil-2,4,6-tridezoksi-2,4-di-C-metil- alpha-L-gliuko-geksopiranozida i metil-2,4,6-tridezoksi-2,4-di-C- metil-alpha-L-manno-geksopiranozina--stereoizomerov fragmenta C33-C38 amfoteritsina B.

The synthesis of the gluco- and manno-stereoisomers of amphotericin B is described.

[Synthetic studies of polyene macrolide antibiotics. 1. Synthesis of C1-C6- and C7-C12 fragments of amphotericin B from carbohydrate precursors]. / Sinteticheskie issledovaniia v riadu polienovykh makrolidnykh antibiotikov. 1. Sintez C1-C6- i C7-C12 fragmentov amfoteritsina B iz uglevodnykh predshestvennikov.

Strategy of synthesis of polyene macrolide antibiotic amphotericin B using carbohydrates as starting material is discussed. The C1-C6 and C7-C12 fragments of amphotericin B are synthesized.

[Synthetic studies of polyene macrolide antibiotics. 2. Synthesis of methyl-4,6-dideoxy-2,3-isopropylidene-4-C-methyl-alpha-L- mannopyranoside]. / Sinteticheskie issledovaniia v riadu polienovykh makrolidnykh antibiotikov. 2. Sintez metil-4,6-didezoksi-2,3-O-izopropiliden-4-C-metil-alpha-L- mannopiranozida.

The synthesis of methyl 4,6-dideoxy-2,3-O-isopropylidene-4-C-methyl-alpha-L-mannopyranoside, a key intermediate on the preparation of C33-C38 fragment of amphotericin B, from L-rhamnose is described.

[Synthetic studies of polyene macrolide antibiotics. 3. Hydrogenation of methyl-6-deoxy-2,3-O-isopropylidene-4-methylene- alpha-L-lyxo-hexopyranoside]. / Sinteticheskie issledovaniia v riadu polienovykh makrolidnykh antibiotikov. 3. Gidrirovanie metil-6-dezoksi-2,3-O- izopropiliden-4-metilen-alpha-L-likso-geksopiranozida.

Experimental conditions of hydrogenation of the title compound are found (excess of Raney catalyst in benzene solution, 5 degrees C, 2h) to afford methyl 4,6-dideoxy-2,3-O-isopropylidene-4-C-methyl-alpha-L-mannopyranoside, the key intermediate in the synthesis of C33-C38 fragment of amphotericin B, with the yield as high as 57%.

On the structure of the teichoic acid from the cell wall of Streptomyces antibioticus 39. Localization of the phosphodiester linkages and elucidation of the monomeric units structure by means of 13C-nuclear-magnetic-resonance spectroscopy.

The cell walls of Streptomyces antibioticus 39 contain a glycosylated poly(glycerol phosphate), in which the repeating monomeric unit is O-alpha-D-galactopyranosyl-(1--3)-O-2-acetamido-2-deoxy-beta-D-galactopyranosyl-(1--1)-glycerol monophosphate. The localization of the phosphodiester linkages between hydroxyl groups at positions 2 and 3 of the adjacent glycerol residues and the structure of the glycoside were established by 13C nuclear-magnetic-resonance spectroscopy. The spectral data are also in accordance with the results of the methylation analysis and enzyme degradation of the glycoside.