Conjugated imines and iminium salts as versatile acceptors of nucleophiles
作者:Makoto Shimizu、Iwao Hachiya、Isao Mizota
DOI:10.1039/b814930e
日期:——
development of synthetic methodologies where nucleophilicaddition reactions to imino carbons are utilized in crucial steps. This article summarizes double nucleophilicaddition reactions with alpha,beta-unsaturated aldimines, addition reactions using alkynyl imines, "umpoled" reactions of alpha-imino esters, and the use of iminium salts as reactive electrophiles.
N-Allylideneamines 1a, b were prepared from acrolein and diphenylethyl or trityl amine in the presence of Ti(OEt)4. Double nucleophilicaddition of various ketene silyl (thio)acetals and trimethylsilyl cyanide to these imines proceeded efficiently to give, after workup with TFA, homoglutamic acid derivatives 3 and valerolactam 5.
Carboboration‐Driven Generation of a Silylium Ion for Vinylic C−F Bond Functionalization by B(C
<sub>6</sub>
F
<sub>5</sub>
)
<sub>3</sub>
Catalysis
作者:Tetsuji Yata、Yoshihiro Nishimoto、Makoto Yasuda
DOI:10.1002/chem.202103852
日期:2022.2
B(C6F5)3-catalyzed reactions between fluoroalkenes and silyl ketene acetals gave vinylic C−F bond-functionalized products under mild and simple conditions. Carboboration reaction of fluoroalkenes generates an oxygen-stabilized silylium ion to facilitate the C−F bond cleavage. DFT and IBO studies were performed to clear the reaction mechanism. A comparative study of α-chloro or bromostyrenes demonstrated
In the presence of silica gel or titanium tetrachloride, ketenesilylacetals or ketenesilyl thioacetals underwent 1,4-addition with α,β unsaturated aldimines which possess a large triphenylmethyl group at the imino nitrogens followed by reduction with sodium cyanoborohydride to give aminopropylated products, δ-amino esters, in good yields.