Mass-spectrometric investigation of hydrocarbons
Summary1. The mass spectra of the diethyl dithioacetals of 2,4:3,5-di-O-benzylidene-D-xylose and 2,4:3,5-di-O-benzylidene-D-ribose have been studied.2. The differences caused by stereochemical factors have been interpreted from the point of view of conformational ideas.
Massenspektrometrische untersuchungen—VII
Zusammenfassung Es wurden die Massenspektren folgender Verbindungen aufgenommen: Methyl-2,3,4-tri-O-methyl-β, d -pyranoside der Ribose, Arabinose, Xylose und Lyxose, Methyl-2,3,4-tri-O-methyl-α, d -lyxopyranosid, Methyl-2,3,5-tri-O-methyl-β, d -arabofuranosid und Methyl-2,3,5-tri-O-methyl-β, d -arabofuranosid-5,5-d 2 . Die Massenspektren ermoglichen eine eindeutige Identifizierung der Stereoisomeren und ihrer Ringgrosse. Der Einfluss von Stereochemie und Ringgrosse kann mit Hilfe der bekannten Fragmentierungsprozesse bei permethylierten Pentosen erklart werden.
Synthesis of 2,4-dideoxy-.beta.-D-erythro-hexopyranosyl nucleosides
The synthesis of 1-(2,4-dideoxy-β-D-erythro-hexopyranosyl)thymine (12) 1 was accomplished using two different synthetic routes. It was obtained starting either from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose or from tri-O-acetyl-D-glucal. The other modified nucleosides, with either a cytosine, guanine, or adenine moiety, were synthesized using the second reaction scheme. Deoxygenation reactions were accomplished with the (2,4-dichlorophenoxy)thiocarbonyl derivatives generated in situ