Abstract:Es wird über eine neue Anwendung von Silicum-Grignard-Reagenzien in der C(sp 3 )-Si-Bindungsknüpfung berichtet. Mit Unterstützung von BF 3 ·OEt 2 addieren diese Siliciumnukleophile unter Kupferkatalyse an Alkene,d ie durch verschiedene Azaarylgruppen aktiviert sind. FürB enzoxazol als Heteroarylsubstituent wurdeeine enantioselektive Variante unter Verwendung eines Cu I -Josiphos-Komplexes entwickelt, mit der die C(sp 3 )-Si-Bindung mit guten bis hohen Enantiomerenverhältnissen gebildet wird (bis zu 97:3). Die … Show more
“…The regio- and stereochemistry of a reaction can be altered depending on the nature of the transition-metal catalyst employed. 155 In 1984, Oshima and co-workers prepared a silylcopper reagent from silylmagnesium, 118 since then various silylcuprates have been prepared in situ by treatment of silylmagnesium, 122 156 157 silylaluminum, 121 155 and silylzinc 155 with a catalytic amount of Cu(I) salt and utilized them in the synthesis of vinylsilanes, 121 155 158 in the alkylation of β-silyl enolates 159 to give exclusively the desired products. 118 119 121 155 158 159 For example, treatment of cyclonona-1,2-diene ( 177 ) with PhMe 2 SiMgMe in the presence of CuI 178 gave almost exclusively 1-(dimethylphenylsilyl)cyclonon-1-ene in an excellent ratio (95:0.5).…”
Section: Silyl Anions Of Transition Metalsmentioning
This review is collective writing on synthetic procedures for the synthesis of different silyl nucleophiles which are valuable reagents for chemists, particularly in the field of organic synthesis and organometallic chemistry. We have described the preparations of silyl nucleophiles of lithium, sodium, potassium, rubidium, and caesium from group I metals. We have also focused on silyl anions of beryllium, magnesium, calcium, strontium, and barium from group II metals. We included synthetic procedures for silyl anions of zirconium, hafnium, cadmium, and zinc. The synthesis of group XIII silyl anions of boron and aluminium is also highlighted in this short review.
“…The regio- and stereochemistry of a reaction can be altered depending on the nature of the transition-metal catalyst employed. 155 In 1984, Oshima and co-workers prepared a silylcopper reagent from silylmagnesium, 118 since then various silylcuprates have been prepared in situ by treatment of silylmagnesium, 122 156 157 silylaluminum, 121 155 and silylzinc 155 with a catalytic amount of Cu(I) salt and utilized them in the synthesis of vinylsilanes, 121 155 158 in the alkylation of β-silyl enolates 159 to give exclusively the desired products. 118 119 121 155 158 159 For example, treatment of cyclonona-1,2-diene ( 177 ) with PhMe 2 SiMgMe in the presence of CuI 178 gave almost exclusively 1-(dimethylphenylsilyl)cyclonon-1-ene in an excellent ratio (95:0.5).…”
Section: Silyl Anions Of Transition Metalsmentioning
This review is collective writing on synthetic procedures for the synthesis of different silyl nucleophiles which are valuable reagents for chemists, particularly in the field of organic synthesis and organometallic chemistry. We have described the preparations of silyl nucleophiles of lithium, sodium, potassium, rubidium, and caesium from group I metals. We have also focused on silyl anions of beryllium, magnesium, calcium, strontium, and barium from group II metals. We included synthetic procedures for silyl anions of zirconium, hafnium, cadmium, and zinc. The synthesis of group XIII silyl anions of boron and aluminium is also highlighted in this short review.
The enantioselective synthesis of chiral azaarenes by rhodium‐catalyzed asymmetric conjugate addition of organoboronic acids to carbonyl‐activated alkenyl azaarenes was reported. Diverse chiral azaarenes were produced in up to 99% yield and with up to 99% ee (>60 examples). Catalytic asymmetric syntheses of dexchlorpheniramine and dexbrompheniramine were realized by using the developed method.magnified image
The activation of pyridinium salts with electronwithdrawing heterocyclese nables an iridium-catalyzedr eductiveh ydroxymethylation reaction to proceed smoothly, facilitating the preparation of useful 3D heteroaryl-substituted functionalized piperidines. The methodology is used to prepare3 -hydroxymethylated analogues of pharmaceuticala gents. Mechanistically,f ormaldehyde acts as both ah ydrided onor and the electrophile, leadingt ot he formation of two new carbon-hydrogen bonds ando ne new carbon-carbon bond under relatively mild conditions.
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