Osamu Tamura

The chemistry of O-silylated ketene acetal; Pummerer rearrangement of sulfoxides into α-siloxysulfides

Abstract Treatment of sulfoxides with ketene silyl acetal in anhydrous acetonitrile in the presence of a catalytic amount of zinc iodide causes a Pummerer rearrangement to give α-siloxysulfides under extremely mild conditions.

The chemistry of O-silylated ketene acetals: an efficientstereocontrolled synthesis of N-benzoyl L-daunosamine

Abstract N-Benzoyl L-daunosamine was synthesized with high stereoselectivity utilizing a 1,3-addition of ketene silyl acetal ( 3a ) to the chiral nitrone,(Z)-[(4R)- trans -2,2,5-trimethyl-1,3-dioxolan-4-yl]methylene[(1S)-1-phenylethyl]amine N-oxide ( 4c ) accompanied by a silyl group-transfer in acetonitrile under mild conditions.

Chemistry of O-silylated ketene acetals1: An efficient synthesis of α-thio-N-heterocycles from ω-amidosulfoxides by a novel intramolecular pummerer-type rearrangement

Abstract Treatment of ω-amidosulfoxides with O -silylated ketene acetals in dry acetonitrile in the presence of a catalytic amount of zinc iodide causes a novel intramolecular Pummerer-type rearrangement to give α-thio- N -heterocycles in high yields.

The chemistry of O-silylated ketene acetals; diastereoselective Aldol reaction of 2,3-O-isopropylidene-D (and L)-glyceraldehydes leading to 2-deoxy-D (and L)-riboses

Abstract Diastereoselective carbon-carbon bond forming reaction of 2,3-O-isopropylidene-D (and L)-glyceraldehydes (D and L-2) with ketene silyl acetals (1a,b) occurred in acetonitrile under mild conditions to give the corresponding anti -β-siloxyesters (D and L-3a) as major products, which could be converted through a few additional steps to 2-deoxy-D(and L)-riboses.

Chemistry of O-silylated ketene acetals: Biomimetic synthesis of cis-β-lactams

Abstract The first successful biomimetic conversion of an Arnstein tripeptide analogue into the cis -β-lactam via a silicon-induced Pummerer-type rearrangement is described.

Cycloaddition of silylene protecting dihydroxystyrene derived from ortho-hydroxyacetophenone: one-step synthesis of peri-hydroxylated polycyclic compounds

Abstract Thermal treatment of the silylene protecting dihydroxystyrene derived from o -hydroxyacetophenone with dienophiles caused a [4+2]cycloaddition to give the corresponding peri -hydroxylated polycyclic aromatic compounds in a single step.

Chemistry of O-silylated ketene acetals: a synthesis of β-lactam antibiotics

β-Amido sulphoxides (2) react with the O-silylated ketene acetal (3) to give the 4-phenylthioazetidin-2-ones (4), which are converted into azetidin-2-one esters (5), known precursors of various types of carbapenem antibiotics.

A novel intramolecular [4+2] cycloaddition of silylene protecting dihydroxystyrene derivatives: A versatile synthesis of linearly condensed peri-hydroxy aromatic compounds

Abstract The first example of an intramolecular [4+2] cycloaddition of the silylene protecting dihydroxystyrene derivatives leading to linearly condensed peri -hydroxy aromatic compounds (6a–c) is described.

Chemistry of O-silylated ketene acetals: a stereoselective synthesis of chiral thienamycin intermediate

A stereoselective synthesis of chiral thienamycin intermediate (10) involving a diastereoselective Michael addition and a silicon-induced Pummerer-type reaction is described.