Tae Kanai

A modification of the asymmetric dihydroxylation approach to the synthesis of (S)-2-arylpropanoic acids

Abstract Catalytic hydrogenolysis of (S)-2-phenyl-1,2-propanediol (2), prepared by an asymmetric dihydroxylation of α-methylstyrene (1) with AD-mix-α, over Pearlmans catalyst gave (S)-2-phenyl-1-propanol (3). This method was applied to the synthesis of optically active 2-arylpropanoic acid anti-inflammatory agents, (S)-ibuprofen (8) and (S)-naproxen (13).

Syntheses of the marine ascidian purine aplidiamine and its 9-β-d-ribofuranoside

Abstract The title nucleoside 9 was synthesized by alkylation of 8-oxoadenosine ( 7 ) with 4-benzyloxy-3,5-dibromobenzyl bromide, followed by Dimroth rearrangement and acid hydrolysis. 2′-Deoxy version of this reaction sequence accomplished the first synthesis of aplidiamine ( 6 ).

Synthesis of [R-(R∗,S∗)]- and [S-(R∗,R∗)]β-hydroxy-3-(β-d-ribofuranosyl)-wybutines, the most probable alternatives for the hypermodified nucleoside of rat liver phenylalanine transfer ribonucleic acid

Abstract The synthesis of the title compounds started with the Vilsmeier reaction of 3-[2,3,5- tris -O-(tert- butyldimethylsilyl)-β- d - ribofuranosyl]wye ( 5b ) and proceeded through the Wittig reaction with ( R )- N -(methoxycarbonyl)-3-(triphenylphosphonio)alaninate ( 4 ), methylation with trimethylsilyldiazomethane, OsO 4 oxidation, cyclocondensation with triphosgene, and catalytic hydrogenolysis. Chromatographic separation of the resulting diastereomeric mixture and subsequent deprotection afforded the two desired nucleoside [ [R-(R ∗ ,S ∗ )]- and [S-(R ∗ ,R ∗ )]- 2b ] for the first time.

Synthesis of β-hydroxywybutines, the most probable alternatives for the hypermodified base of rat liver phenylalanine transfer ribonucleic acid☆

Abstract Deoxygenation of the 1,2-glycol (±)-5 was achieved at the position adjacent to the heterocycle through the cyclic carbonate (±)-14, providing the monohydroxy compound 6. This new method of regioselective deoxygenation was employed for the first synthesis of β-hydroxywybutines [[R-(R ∗ ,S ∗ )]- and [S-(R ∗ ,R ∗ )]-2] : oxidation of the methyl butenoate 7 with osmium tetroxide, followed by deoxygenation through the cyclic carbonates (19 and 20), afforded the two diastereomers of 2.

STRUCTURES OF CONDENSED TRICYCLIC NUCLEOSIDES OF PHENYLALANINE TRANSFER RIBONUCLEIC ACIDS

Abstract The unstable minor nucleosides, wyosine, wybutosine, and β-hydroxywybutosine, were isolated from tRNAs in sufficient amounts for determination of their structures.