Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tinreagents, the reaction took place chemoselectively at the carbon–iodine bond but not at the carbon–bromine or carbon–chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant
氰基硼氢化物是烷基碘化物和缺电子烯烃的还原加成反应中的有效试剂。与使用锡试剂相反,该反应在碳碘键上发生化学选择,而在碳溴或碳氯键上没有发生。该反应体系已成功应用于三组分反应,包括自由基羰基化。通过动力学竞争法,在25°C下从氰基硼氢化四丁基铵中伯烷基脱氢的速率常数估计为<1×10 4 M –1 s –1。该值比氢化三丁基锡的值小3个数量级。
Stereoselective Synthesis of Trisubstituted Alkenes through Sequential Iron-Catalyzed Reductive<i>anti</i>-Carbozincation of Terminal Alkynes and Base-Metal-Catalyzed Negishi Cross-Coupling
作者:Chi Wai Cheung、Xile Hu
DOI:10.1002/chem.201504049
日期:2015.12.7
stereoselective synthesis of trisubstituted alkenes is challenging. Here, we show that an iron‐catalyzed anti‐selective carbozincation of terminal alkynes can be combined with a base‐metal‐catalyzed cross‐coupling to prepare trisubstituted alkenes in a one‐pot reaction and with high regio‐ and stereocontrol. Cu‐, Ni‐, and Co‐based catalytic systems are developed for the coupling of sp‐, sp2‐, and sp3‐hybridized
Tin-free Giese reaction and the related radical carbonylation process proceeded efficiently in the presence of sodium cyanoborohydride and tetrabutylammonium cyanoborohydride. The reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine and carbon-chlorine bonds. The iodine atom transfer followed by hydride reduction of the resulting carbon-iodine bond is proposed
1-HALOALKADIENE AND A PROCESS FOR PREPARING THE SAME AND A PROCESS FOR PREPARING (9e, 11z)-9,11-HEXADECADIENYL ACETATE
申请人:SHIN-ETSU CHEMICAL CO., LTD.
公开号:US20190322614A1
公开(公告)日:2019-10-24
A process to prepare (9E,11Z)-9,11-hexadecadienyl acetate with a good yield and high purity of the general formula (1): CH
3
—(CH
2
)
3
—CH═CH—CH═CH—(CH
2
)
a
—X.=The process includes a step of conducting a Wittig reaction between a haloalkenal of the general formula (2): OHC—CH═CH—(CH
2
)
a
—X, and a triarylphosphonium pentylide of the general formula (3): CH
3
—(CH
2
)
3
—CH
−
—P
+
Ar
3
, to obtain the 1-haloalkadiene, and the use of a (7E,9Z)-1-halo-7,9-tetradecadiene obtained by the process for a process of preparing (9E, 11Z)-9,11-hexadecadienyl acetate.
Transition metal compound, polymerization-initiator system comprising the same, and process for producing polymer
申请人:Uemura Makoto
公开号:US20070270521A1
公开(公告)日:2007-11-22
A transition metal compound represented by the formula, [(CpR
1
m
)(CO)
2
M
1
][M
2
(CO)
2
(CpR
2
n
)], wherein Cp is a cyclopentadienyl ring, R
1
and R
2
are independently of each other a hydrocarbyl group having 1 to 20 carbon atoms, and each of at least one R
1
and at least one R
2
is a hydrocarbyl group having 5 to 20 carbon atoms, m and n are independently of each other an integer of 1 to 5, and M
1
and M
2
are independently of each other a transition metal atom of the group 8 in the periodic table of elements; a polymerization-initiator system comprising said transition metal compound; and a process for producing a polymer in the presence of the polymerization-initiator system.