Synthesis of Ceramides Bearing DL-erythro- and DL-threo-Cn-Dihydrosphingosines, and the Determination of the erythro and threo Isomers by Mass Spectrometry

Abstract

DL-threo-and DL-erythro-Cn-dihydrosphingosines (n=12, 14, and 16) were separated from the corresponding 2-amino-1, 3-alkanediols by repeated recrystallization of the N, O, O-triacetyl and N-acetyl derivatives. Ceramides having DL-threo-and DL-erythro-Cn-dihydrosphingosines were prepared by reactions of the bases with N-acyloxysuccinimides in tetrahydrofuran. CLC-MS analysis of O, O-di-TMS derivatives of the ceramides was carried out to find differences between threo and erythro isomers in mass spectra. One characteristic difference was observed in the relative intensity (RI) at m/e=M-103; i.e., the relative intensities of threo compounds (RI 40•`80%) were stronger than those of erythro isomers (RI 6•`14%). The ratios, RI(M-103)/RI(M-15), were 3.7•`6.8 and 0.8•`1.3 for threo and erythro compounds, respectively. These observations demonstrate the possibility of determining erythro and threo isomers by mass spectrometry.

Chemistry of Succinimido Esters. IV.

“…(1) involving long chain acyl residue [CN=818, CN : carbon number of the acyl group in (1)] react spec cifically with amino group in sphingolipid bases such as sphingosine and dihydrosphin= gosines to give N-acyl compounds (ceramic des) '' '2'. It is reported that (1) can be prepared by the coupling reaction of fatty acid and HOSu*2 in the presence of DCC*2 in aprotic solvents.…”

“…In the case of DSC, HOSu and pyridine were easily re moved by the water treatment as for (1) . Purities were more than 99% after the water treatment.…”

Chemistry of Succinimido Esters. VIII.

“…Thus, the rate was measured in 0.1 M buffer in the prey sent studies. Furthermore, we employed the reaction condition of [2]0> [1], to simplify the kinetics.…”

“…In the present paper, we selected aliphatic primary amines (2) as subv strates and studied kinetically the N arylcarv bonylation of (2) by (1) in aqueous solution to discover a possibility as a labelling reagent for the amino compounds which do not have absorbance at 254 or 280 nm, and the precise mechanism of the N arylcarbonylation by (1). (1) were prepared by the previously reported method'' using DSC*2. Purity of (1) exceeded 99% by GLC and HPLC analyses.…”

“…The reactions of N-succinimidyl benzoates (1) with aliphatic primary amines (2) (RNH2 : R= n-Pr, iso-Pr, n-Bu, s-Bu, t-Bu, and n-Am) were studied kinetically at 25°C in aqueous solution (7.0 N-arylcarbonylation was competitive with the decomposition of (1)…”