Akira Arase

Dialkylborane-Catalyzed Hydroboration of Alkynes with 1,3,2-Benzodioxaborole in Tetrahydrofuran

Abstract Dialkylborane catalyzed hydroboration of alkynes with an equimolar amount of 1,3,2-benzodioxaborole in tetrahydrofuran efficiently to provide 2-alkenyl-1,3,2-benzodioxaborole under mild reaction conditions.

Dicyclohexylborane-Catalyzed Hydroboration of 1-Halo-1-alkynes with 9-Borabicyclo[3.3.1]nonane

Abstract A catalytic amount of dicyclohexylborane accelerates the hydroboration of 1-halo-1-alkyne (1) with 9-BBN to provide B-[(Z)-1-halo-1-alkenyl]-9-BBN (2) regio- and stereo-selectively.

Stereoselective Synthesis of (E)- and (Z)-1-Alkenyltributylstannanes From (E)- and (Z)-1-Alkenyldialkylboranes Using a Cross-Coupling Reaction with Tributyltin Halide

Abstract The cross-coupling reaction of ( E )- or ( Z )-1-alkenyldialkylborane with tributyltin halide using copper (II) acetylacetonate [Cu(acac) 2 ] as catalyst in the presence of NaOH proceeds under extremely mild and aqueous conditions to give ( E )- or ( Z )-1-alkenyltributylstannane stereoselectively.

REACTIONS OF ALKYLMAGNESIUM HALIDES AND ALKYLLITHIUMS WITH SELENIUM DIOXIDE. A NEW ROUTE TO DIALKYL SELENIDE

Alkylmagnesium halides and alkyllithiums reacted with selenium dioxide, suspended in tetrahydrofuran, to afford dialkyl selenides in 30–62 % yields.

A new facile route to primary alkanenitriles from terminal alkenes via a hydroboration–cyanation sequence

Terminal alkenes are converted into one-carbon homologated primary alkanenitriles in high yields via hydroboration followed by a reaction with copper(I) cyanide, copper(II) acetate, and copper(II) acetylacetonate.

Stereoselective dehalogenation of (Z)-1-halo-1-alkenyldialkylborane with tributyltin hydride: The behavior of tributyltin hydride as a hydride donor

Abstract The reaction of (Z)-1-halo-1-alkenyldialkylborane (1) with tributyltin hydride (n-Bu3SnH) at 0 °C or room temperature results in reductive removal of the halogen atom to afford (E)- or (Z)-1-alkenyldialkylborane whose stereochemistry depends on the dialkylboryl group and the alkenyl group of 1.

A new simple synthesis of isomerically pure α,β-unsaturated nitriles via hydroboration of alkynes

Terminal alkynes are converted into (E)-1-cyanoalk-1-enes in good yields via hydroboration followed by reaction with copper(I) cyanide and copper(II) acetate in the presence of a small amount of water, in hexamethylphosphoric triamide.

The hydroboration of (trimethylsilyl)ethyne with dialkylboranes and its application to the syntheses of (E)-1-(trimethylsilyl)alk-1-enes and 2-(trimethylsilyl)alk-1-enes

The reaction of (trimethylsilyl)ethyne 1 with a stoicheiometric amount of dialkylborane 2 proceeds to the monohydroboration stage, giving a mixture of regioisomers, (E)-[2-(trimethylsilyl)-ethenyl]dialkylborane 3 and [1-(trimethylsilyl)ethenyl]dialkylborane 4. In the hydroboration with bulky dialkylboranes, derived from internal alkenes, the former predominates. Successive treatment of the mixture with methyllithium and benzenesulphenyl chloride exclusively affords highly pure (E)-2-alkyl-1-(trimethylsilyl)ethene 6 whose alkyl group migrates from the boron atom, while in the hydroboration with less bulky dialkylboranes, derived from terminal alkenes, the latter predominates. Successive treatment of the mixture with aq. NaOH and iodine exclusively affords highly pure 2-(trimethylsilyl)alk-1-ene 7 whose alkyl group migrates from the boron atom.

A new synthesis of 2-alkylbuta-1,3-dienes from internal alkenes and 1,4-dichlorobut-2-yne via dialkyl(1,4-dichlorobut-2-en-2-yl)boranes

The successive treatment of borane in tetrahydrofuran with sterically-hindered internal alkenes, 1,4-dichlorobut-2-yne, and alkyl-lithium has provided good yields of 2-alkylbuta-1,3-dienes whose alkyl groups are derived from the alkene.

Syntheses of 2-t-alkylbuta-1,3-dienes and 2-alkylthiobuta-1,3-dienes from 1,4-dichlorobut-2-yne via alkenylboranes

2-t-Alkylbuta-1,3-dienes were synthesized by the successive reaction of dialkylboranes, derived from tetrasubstituted ethenes and borane in tetrahydrofuran, with 1,4-dichlorobut-2-yne and methyl-lithium; 2-alkylthiobuta-1,3-dienes were synthesized by a similar reaction using alkylthiomagnesium bromides instead of methyl-lithium.