38610-96-7Relevant articles and documents
Generation of carbanions through stibine-metal and bismuthine-metal exchange reactions and its applications to precision synthesis of ω-end-functionalized polymers
Kayahara, Eiichi,Yamada, Hiroto,Yamago, Shigeru
, p. 5272 - 5280 (2011)
Generation of carbanions from organostibines and organobismuthines through heteroatom-metal exchange reactions was examined from synthetic and mechanistic viewpoints. The exchange reaction proceeded spontaneously upon treatment with various organometallic reagents, such as alkyl lithiums, tetraalkyl zincates, and alkyl magnesium halides to afford the corresponding carbanions quantitatively. Due to the high reactivity of these heteroatom compounds, the exchange reactions took place exclusively even in the presence of various polar functional groups, which potentially react with organometallic species. The advantage of this method was exemplified by the end-group transformation of living polymers that bear these heteroatom species at the ω-polymer end, prepared by using organostibine and bismuthine-mediated living radical polymerizations. Various polymers that bear polar functional groups and acidic hydrogen-for example, poly(methyl methacrylate), poly(butyl acrylate), poly(N-isopropyl acrylamide), and poly(2-hydroxyethyl methacrylate)-could be used in the exchange reactions, and subsequent trapping with electrophiles afforded the corresponding polymers with controlled molecular weights, molecular weight distributions, and end-group functionalities. Competition experiments showed that organostibines and organobismuthines were among the most reactive heteroatom compounds towards organometallic reagents and that their high reactivity was responsible for the high chemoselectivity in the exchange reaction. All's well that ends well: The generation of carbanions from organostibine and -bismuthine compounds was achieved thorough a heteroatom-metal exchange reaction (see scheme). The highly chemoselective exchange reaction could be applied to precision synthesis of varieties of ω-end- functionalized polymers that possess a polar functional group.
Easy access to secondary and tertiary alcoholsviametal-free and light mediated radical carbonyl allylation
Das, Mrinmoy,Lee, Jiande,Lin, Junjie Desmond,Liu, Xue-Wei,Pal, Kumar Bhaskar,Xu, Yuan,Yip, Benjamin Rui Peng
supporting information, p. 10783 - 10786 (2021/10/20)
Here we report a strategy for carbonyl addition with unactivated alkenes using an organic photocatalyst on both aldehyde and ketone substrates. This protocol grants us a good alternative to the traditional Barbier-Grignard allylation that exhibits poor functional group tolerance. With this method the stoichiometric use of metals can be avoided, high atom economy can be achieved and fewer by-products are generated.
Chemoselective Preparation of Ketones by the Grignard Reaction of N-Acylpyrazoles
Kashima, Choji,Kita, Isanobu,Takahashi, Katsumi,Hosomi, Akira
, p. 25 - 28 (2007/10/02)
N-Acylpyrazoles afford chemoselectively the corresponding ketones in good yields by the use of equimolar amounts of Grignard reagent.In the case of an optically active N-acylpyrazole, optical asymmetry was retained in comparable optical yield.Ketone formation by the Grignard reactions can be regarded as an important functionalization in a synthetic loop using pyrazoles as the auxiliary compound.
