4798-58-7Relevant articles and documents
Synthetic and Computational Study of Tin-Free Reductive Tandem Cyclizations of Neutral Aminyl Radicals
Sirinimal, Hansamali S.,Hebert, Sebastien P.,Samala, Ganesh,Chen, Heng,Rosenhauer, Gregory J.,Bernhard Schlegel,Stockdill, Jennifer L.
supporting information, p. 6340 - 6344 (2018/10/09)
5-exo, 5-exo Cyclizations of conformationally unbiased propargylic aminyl radicals proceed with excellent yield, chemoselectivity, and diastereoselectivity under tin-free reductive cyclization conditions, regardless of the electronic environments and intermediate radical stabilization resulting from various olefin substituents. These conditions avoid the need for slow addition of initiator and reductant. By contrast, analogous 6-exo, 5-exo cyclizations require substituents capable of intermediate radical stabilization to avoid premature reduction products. These experimental results are corroborated by computations that further establish the reactivity of these aminyl radicals upon exposure to tin-free cyclization conditions.
Preparation of stereodefined homoallylic amines from the reductive cross-coupling of allylic alcohols with imines
Chen, Ming Z.,McLaughlin, Martin,Takahashi, Masayuki,Tarselli, Michael A.,Yang, Dexi,Umemura, Shuhei,Micalizio, Glenn C.
supporting information; experimental part, p. 8048 - 8059 (2011/02/26)
Regio-, diastereo-, and enantioselective coupling reactions between imines and allylic alcohols have been developed. These coupling reactions deliver complex homoallylic amine products through a convergent C-C bond forming process that does not proceed through intermediate allylic organometallic reagents. In general, convergent coupling, by exposure of an allylic alkoxide to a preformed Ti-imine complex, occurs with allylic transposition in a predictable and stereocontrolled manner. While simple diastereoselection in these reactions is high, delivering anti-products with ≥20:1 selectivity, the organometallic transformation described is compatible with a diverse range of functionality and substrates (including aliphatic and aromatic imines, allylic silanes, trisubstituted alkenes, vinyl- and aryl halides, trifluoromethyl groups, thioethers, and aromatic heterocycles). Alkene geometry of the products is a complex function of the allylic alcohol structure and is consistent with a mechanistic proposal based on syn-carbometalation followed by syn-elimination by way of a boat-like transition state geometry. Single asymmetric coupling reactions provide a means to translate the stereochemical information of the allylic alcohol to the homoallylic amine or to control diastereoselection in the coupling reactions of achiral allylic alcohols with chiral imines. Double asymmetric coupling reactions are also described that afford a unique means to control stereoselection in these complex convergent coupling processes. Finally, empirical models are proposed that are consistent with the observed stereochemical course of these coupling reactions en route to chiral homoallylic amines possessing di- or trisubstituted alkenes and anti- or syn- relative stereochemistry at the allylic and homoallylic positions.
Reduction of α,β-unsaturated ketones with diphenylsilanes bearing several substituents on their phenyl moiety catalyzed by rhodium-phosphine complexes
Imao, Daisuke,Hayama, Miyuki,Ishikawa, Kohta,Ohta, Tetsuo,Ito, Yoshihiko
, p. 366 - 367 (2007/10/03)
1,4-Addition product was afforded exclusively by rhodiumphosphine complex-catalyzed hydrosilylation by using 2-cyclohexen-1-one and a dihydrosilane bearing an ether substituent in spite of the fact that dihydrosilanes were believed to give 1,2-addition product selectively. Copyright
