Osamu Tamura

Yasuyuki Kita; Hitoshi Yasuda; Osamu Tamura; Fumio Itoh; Yasumitsu Tamura

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.

Yasuyuki Kita; Fumio Itoh; Osamu Tamura; Ya Yuan Ke; Yasumitsu Tamura

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.

Yasuyuki Kita; Osamu Tamura; Takashi Miki; Yasumitsu Tamura

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.

Yasuyuki Kita; Hitoshi Yasuda; Osamu Tamura; Fumio Itoh; Yuan Ke Ya; Yasumitsu Tamura

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.

Yasuyuki Kita; Osamu Tamura; Takashi Miki; Hideyuki Tono; Norio Shibata; Yasumitsu Tamura

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.

Yasuyuki Kita; Hitoshi Yasuda; Osamu Tamura; Yasumitsu Tamura

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.

Yasuyuki Kita; Osamu Tamura; Norio Shibata; Takashi Miki

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.

Yasuyuki Kita; Ryuichi Okunaka; Takao Honda; Miki Shindo; Osamu Tamura

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.

Yasuyuki Kita; Norio Shibata; Takashi Miki; Yumiko Takemura; Osamu Tamura

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

Yasuyuki Kita; Osamu Tamura; Fumio Itoh; Hitoshi Yasuda; Takashi Miki; Yasumitsu Tamura