Darstellung und “disproportionierende Hydrolyse” von Cyclopropanonthioacetalen Eine neue Homologisierungsmethode1, 2)

Asymmetric total synthesis of complex marine natural products

Among nature's ecosystems, the marine environment has been an extremely rich source of structurally complex and biologically active molecules. This review aims to cover the recent developments in the synthesis of marine natural products, also reflecting the trend of their increased use to address biological questions. The examples chosen should be viewed as representative of the different structural motifs on the one hand and the strategies and stimuli for their synthesis on the other.

Application of cyclic sulfates in the synthesis of 6-deoxy-D-manno-heptopyranose derivatives

6-Deoxy-D-manno-heptopyranose was prepared in five steps starting from methyl 2,3-O-isopropylidene-alpha-D-mannopyranoside 4,6-sulfate or methyl 2,3-O-isopropylidene-alpha-D-mannofuranoside 5,6-sulfate. The glycosyl donor ethyl 2,3,4,7-tetra-O-benzoyl-6-deoxy-1-thio-alpha,beta-D-manno- heptopyranoside was used to synthesize methyl 4-O-(6-deoxy-alpha-D-manno-heptopyranosyl)-beta-D-galactopyranoside.

An asymmetric approach to 2-deoxynucleosides via organosulfur building blocks as chemical chameleons

An asymmetric synthesis of 6-N-benzoyl-5'-O-benzyl-2'-deoxyadenosine and its a anomer from non-carbohydrate building blocks is achieved in 7 steps. The sequence builds the basic structures using bis(methylthio)methane and methylthiomethyl phenyl sulfone as both nucleophilic and electrophilic building blocks, a feature that suggests their behavior as chemical chameleons. The asymmetric induction is achieved utilizing a kinetic resolution based upon catalytic asymmetric epoxidation.