The first and convenient synthesis of acyclic dienediynes related to neocarzinostatin chromophore
摘要:
A stereocontrolled and flexible synthetic approach to acyclic (E,E) and (Z,E)-dienediynes, related to the neocarzinostatin chromophore 5, from readily available stannylated chlorodienes 1 and dienynes 2 is described. (C) 1998 Elsevier Science Ltd. All rights reserved.
Regiocontrol of the Palladium-Catalyzed Tin Hydride Addition to Z-Enynols: Remarkable Z-Directing Effects
摘要:
[GRAPHICS]Palladium-catalyzed hydrostannation of substituted Z- and E-enynols is discussed and compared. The regioselectivity of the H-Sn bond addition was found to be controlled by the geometry of the double bond ( Z- or syn-directing effect) rather than the nature of its substituents. Exclusively alpha-vinyl stannanes were obtained from Z-enynols having various substituents on the double bond regardless of their electronic, steric, or chelating natures.
letter reports the preparation of quinolines, substituted at the 2- or 3-position by a 4-substituted but-3-en-1-yne group, by the environmentally friendly iron(III)-catalyzed coupling reaction of Grignardreagents with 1-chloro-4-(2-quinolyl)but-1-en-3-yne. The extension and the scope of this non-toxic and chemoselective procedure to various functionalized unsaturated vinyl chlorides are described.
Under palladium catalysis, we found that organozincate reagents, generated in situ, by reaction of Grignard compounds with less than molar amounts of zinc chloride, in the presence of conjugated alkenyl chlorides, give rapidly and cleanly the corresponding coupling product in high yields. In this way, aryl as well as primary and secondary alkyl substituents have been introduced successfully. The selectivity of the reaction allows to prepare various functionalized conjugated enynes and dienes from chloroenyne and chlorodiene derivatives bearing a functional group. (C) 2003 Elsevier Ltd. All rights reserved.
Stereoselective synthesis of (E)-chloroenynes or (E,E)-chlorodienes starting from a stereoisomeric mixture of 1,2-dichloroethylenes
Under palladium or nickel catalysis. a stereomeric mixture 1:1 of (Z) and (E)-1,2-dichloroethylene readily reacts with 1-alkynes. vinyl alanes or vinyl boranes to afford selectively the corresponding (E)-coupling product in good to excellent isolated yields. The selectivity of this coupling reaction is discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.
Regiocontrol of the Palladium-Catalyzed Tin Hydride Addition to <i>Z</i>-Enynols: Remarkable <i>Z</i>-Directing Effects
[GRAPHICS]Palladium-catalyzed hydrostannation of substituted Z- and E-enynols is discussed and compared. The regioselectivity of the H-Sn bond addition was found to be controlled by the geometry of the double bond ( Z- or syn-directing effect) rather than the nature of its substituents. Exclusively alpha-vinyl stannanes were obtained from Z-enynols having various substituents on the double bond regardless of their electronic, steric, or chelating natures.
The first and convenient synthesis of acyclic dienediynes related to neocarzinostatin chromophore
作者:Murielle Bujard、Fabiola Ferri、Mouaˆd Alami
DOI:10.1016/s0040-4039(98)00693-5
日期:1998.6
A stereocontrolled and flexible synthetic approach to acyclic (E,E) and (Z,E)-dienediynes, related to the neocarzinostatin chromophore 5, from readily available stannylated chlorodienes 1 and dienynes 2 is described. (C) 1998 Elsevier Science Ltd. All rights reserved.