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. 6. Synthesis of methyl-2,4,6-trideoxy-2,4-dimethyl-alpha-altro- hexopyranoside, the C33-C38 fragment of amphotericin 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].

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

[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].

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.