The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Masayuki Hoshi - One of the best experts on this subject based on the ideXlab platform.
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preparation of e 1 Alkenylboronic acid pinacol esters via transfer of Alkenyl Group from boron to boron
Synthesis, 2004Co-Authors: Kazuya Shirakawa, Akira Arase, Masayuki HoshiAbstract:Two synthetic routes to (E)-1-Alkenylboronic acid pinacol esters 3 were investigated. Hydroboration of 1-alkynes I with 1,3,2-benzodioxaborole (catecholborane), in situ generated by the reaction of BH 3 in THF with catechol, proceeded in the presence of a catalytic amount of dicyclohexylborane in THF at room temperature to give the corresponding (E)-1-Alkenylboronic acid catechol esters 2. Treatment of the resultant esters 2 with 2,3-dimethyl-2,3-butanediol (pinacol) easily afforded the desired products 3, which are insensitive to air, moisture and chromatography, in good to high overall yields. The sequential reaction is a highly efficient route to 3 from BH 3 in THF in a one-pot manner. Alternatively, hydroboration of 1 with 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane) was achieved in the presence of a catalytic amount of dicyclohexylborane at room temperature under neat conditions to afford the corresponding products 3 directly in good to excellent yields. This route is extremely efficient and environmentally benign from the viewpoints of making good use of pinacolborane and of using no solvent, and is capable of using a variety of alkynes 1 including functionalized ones such as HCCCH 2 Cl and HCCCH 2 OTHP.
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Stereoselective dehalogenation of (Z)-1-halo-1-Alkenyldialkylborane with tributyltin hydride: The behavior of tributyltin hydride as a hydride donor
Tetrahedron Letters, 1997Co-Authors: Masayuki Hoshi, Kimitomo Takahata, Akira AraseAbstract: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.
Akira Arase - One of the best experts on this subject based on the ideXlab platform.
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preparation of e 1 Alkenylboronic acid pinacol esters via transfer of Alkenyl Group from boron to boron
Synthesis, 2004Co-Authors: Kazuya Shirakawa, Akira Arase, Masayuki HoshiAbstract:Two synthetic routes to (E)-1-Alkenylboronic acid pinacol esters 3 were investigated. Hydroboration of 1-alkynes I with 1,3,2-benzodioxaborole (catecholborane), in situ generated by the reaction of BH 3 in THF with catechol, proceeded in the presence of a catalytic amount of dicyclohexylborane in THF at room temperature to give the corresponding (E)-1-Alkenylboronic acid catechol esters 2. Treatment of the resultant esters 2 with 2,3-dimethyl-2,3-butanediol (pinacol) easily afforded the desired products 3, which are insensitive to air, moisture and chromatography, in good to high overall yields. The sequential reaction is a highly efficient route to 3 from BH 3 in THF in a one-pot manner. Alternatively, hydroboration of 1 with 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane) was achieved in the presence of a catalytic amount of dicyclohexylborane at room temperature under neat conditions to afford the corresponding products 3 directly in good to excellent yields. This route is extremely efficient and environmentally benign from the viewpoints of making good use of pinacolborane and of using no solvent, and is capable of using a variety of alkynes 1 including functionalized ones such as HCCCH 2 Cl and HCCCH 2 OTHP.
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Stereoselective dehalogenation of (Z)-1-halo-1-Alkenyldialkylborane with tributyltin hydride: The behavior of tributyltin hydride as a hydride donor
Tetrahedron Letters, 1997Co-Authors: Masayuki Hoshi, Kimitomo Takahata, Akira AraseAbstract: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.
Susumu Takada - One of the best experts on this subject based on the ideXlab platform.
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intermolecular transfer of an Alkenyl Group in enamines application to synthesis of b fused pyridines
Tetrahedron Letters, 1996Co-Authors: Makoto Adachi, Takashi Sasatani, Nobuo Chomei, Susumu TakadaAbstract:Abstract A novel intermolecular Alkenyl transfer of enamines was developed for the preparation of cycloAlkenylaminomethyleneoxazolones, which were thermally cyclized to [ b ]-fused pyridines in good yields. The functional manipulation of the pyridines provided versatile precursors for further annulation to tricyclic ring systems.
Shujiang Tu - One of the best experts on this subject based on the ideXlab platform.
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organocatalytic chemo e z and enantioselective formal Alkenylation of indole derived hydroxylactams using o hydroxystyrenes as a source of Alkenyl Group
Journal of Organic Chemistry, 2014Co-Authors: Honghao Zhang, Yueming Wang, Shujiang TuAbstract:The first organocatalytic asymmetric formal Alkenylation of multicyclic alcohols using non-metal-based alkenes instead of Alkenyl metals as a source of an Alkenyl Group has been established via chiral phosphoric acid catalyzed tandem reactions. This transformation directly assembles isoindolo-β-carboline-derived hydroxylactams with o-hydroxystyrenes via an asymmetric cascade vinylogous addition/hydrogen elimination reaction sequence, offering an easy access to functionalized chiral isoindolo-β-carbolines with one quaternary stereogenic center in high chemo-, (E/Z)-, and enantioselectivities (up to >95:5 cr, >95:5 E/Z, 97:3 er). This approach also represents the first catalytic asymmetric formal Alkenylation of isoindolo-β-carboline-derived hydroxylactams, which provides a useful strategy for functionalization of isoindolo-β-carbolines and synthesis of chiral isoindolo-β-carboline derivatives. In addition, the investigation on the activating mode revealed that the hydroxyl Group in o-hydroxystyrene was ess...
Miwako Mori - One of the best experts on this subject based on the ideXlab platform.
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Carbon−Carbon Bond Formation via the Transmetalation of an Alkenyl Group on Azazirconacyclopentene
Organometallics, 1996Co-Authors: T Honda, Miwako MoriAbstract:The transmetalation of azazirconacyclopentene 1, prepared by inserting alkyne 8 into azazirconacyclopropane 7, was realized, and the zirconium−carbon bond of complex 1 was transformed to a carbon−carbon bond using a copper(I) salt. Thus, both allyl and formyl Groups can be introduced into alkyne carbons in a highly stereoselective manner in a one-pot reaction.
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carbon carbon bond formation via the transmetalation of an Alkenyl Group on azazirconacyclopentene
Organometallics, 1996Co-Authors: T Honda, Miwako MoriAbstract:The transmetalation of azazirconacyclopentene 1, prepared by inserting alkyne 8 into azazirconacyclopropane 7, was realized, and the zirconium−carbon bond of complex 1 was transformed to a carbon−carbon bond using a copper(I) salt. Thus, both allyl and formyl Groups can be introduced into alkyne carbons in a highly stereoselective manner in a one-pot reaction.
