Synthesis of C-glycosides via a palladium mediated coupling reaction of an aryl stannane and a glycal. A study directed toward the synthesis of the gilvocarcins
Tetrahydrodibenzocoumarin and benzonaphthopyranone ..beta..-C-glycosides, similar in structure to the antibiotic gilvocarcins, were synthesized selectively at room temperature using palladium-mediated coupling reactions between furanoid glycals (1,2-unsaturated sugars) and the corresponding tri(n-butyl)stannyl aglycones (1',2',3',4'-tetrahydro-3,4,7,8-dibenzocoumarins and benzo(d)naphtho(1,2-b)pyran-6-ones, respectively). Controlled formation of ..beta..-C-glycosides was accomplished by appropriate choice of substituents for the glycal hydroxy groups. Removal of protecting groups from the furanoid coupled products yielded 2'-deoxy-3'-keto-C-glycosides which upon metal hydride reduction produced the corresponding 2'-deoxy-C-glycosides. Structural assignments of the tetrahydrodibenzocoumarin and benzonaphthopyranone C-glycosides were confirmed by /sup 1/H- and /sup 13/C-NMR spectral data. This study represented the first use of trialkylstannanes as precursors in the synthesis of C-glycosides using the Heck-type palladium-mediated coupling reaction. Trialkylstannane precursors were investigated due to the low solubility of tetrahydrodibenzocoumarin mercury derivatives which precluded their use. A comparison between acetoxymercuryl- and tri(n-butyl)stannyl aglycones in the palladium-mediated coupling reaction with furanoid and pyranoid glycals demonstrated that the tri(n-butyl)stannyl aglycone is as effective as a mercuryl aglycone. However, the tri(n-butyl)stannyl aglycone is more soluble in organic solvents and can be used in instances where the mercuryl aglycone is too insoluble to be used.
- Research Organization:
- Lehigh Univ., Bethlehem, PA (USA)
- OSTI ID:
- 5845434
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
BARYONS
CARBOHYDRATES
CARBON 13
CARBON ISOTOPES
CATALYTIC EFFECTS
CHEMICAL PREPARATION
COMPLEXES
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
FERMIONS
GLYCOSIDES
HADRONS
ISOTOPES
LIGHT NUCLEI
NMR SPECTRA
NUCLEI
NUCLEONS
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PALLADIUM COMPLEXES
PROTONS
SPECTRA
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES