851293-07-7Relevant academic research and scientific papers
Stereospecific copper(II)-catalyzed tandem ring opening/oxidative alkylation of donor-acceptor cyclopropanes with hydrazones: Synthesis of tetrahydropyridazines
Mishra, Manmath,De, Pinaki Bhusan,Pradhan, Sourav,Punniyamurthy, Tharmalingam
, p. 10901 - 10910 (2019/09/13)
Aerobic copper(II)-catalyzed tandem ring opening and oxidative C-H alkylation of donor-acceptor cyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89-98% enantiomeric excess). The substrate scope, functional group tolerance, dual role of the copper(II) catalyst, and the use of air as an oxidant are the important practical features. A product bearing a 3-bromoaryl group can be subjected to Pd-catalyzed Suzuki coupling with boronic acid in high yield.
A chiral cagelike copper(I) catalyst for the highly enantioselective synthesis of 1,1-cyclopropane diesters
Deng, Chao,Wang, Li-Jia,Zhu, Jun,Tang, Yong
supporting information, p. 11620 - 11623,4 (2012/12/12)
Triangulation method: The catalytic enantioselective cyclopropanation of multisubstituted olefins with phenyliodonium ylide malonate has been achieved in the presence of a chiral bisoxazoline copper(I) complex (see scheme). A wide range of substrates undergo the reaction to provide optically active 1,1-cyclopropane diesters in high yield with up to >99 %-ee. A rationale for the enantioselective induction has been proposed. Copyright
A chiral cagelike copper(I) catalyst for the highly enantioselective synthesis of 1,1-cyclopropane diesters
Deng, Chao,Wang, Li-Jia,Zhu, Jun,Tang, Yong
supporting information, p. 11620 - 11623 (2013/01/15)
Triangulation method: The catalytic enantioselective cyclopropanation of multisubstituted olefins with phenyliodonium ylide malonate has been achieved in the presence of a chiral bisoxazoline copper(I) complex (see scheme). A wide range of substrates undergo the reaction to provide optically active 1,1-cyclopropane diesters in high yield with up to >99 %-ee. A rationale for the enantioselective induction has been proposed. Copyright
Asymmetric cyclopropanation of alkenes with dimethyl diazomalonate catalyzed by chiral diene-rhodium complexes
Nishimura, Takahiro,Maeda, Yuko,Hayashi, Tamio
supporting information; experimental part, p. 7324 - 7327 (2010/11/18)
Chiral tridentate ligand : A chiral dienerhodium complex (1; see scheme) was found to catalyze the intermolecular asymmetric cyclopropanation of alkenes with dimethyl diazomalonate to give 1,1-cyclopropane diesters in good yields and with high enantioselectivity.
Highly enantioselective and diastereoselective cycloaddition of cyclopropanes with nitrones and its application in the kinetic resolution of 2-substituted cyclopropane-1,1-dicarboxylates
Kang, Yan-Biao,Sun, Xiu-Li,Tang, Yong
, p. 3918 - 3921 (2008/03/11)
(Chemical Equation Presented) The multitalented catalyst 1/Ni(ClO 4)2 mediates both title processes (see scheme). Together the efficient asymmetric cycloaddition and a kinetic resolution/ cycloaddition provide access to both enantiom
Rhodium(II)-catalyzed inter- and intramolecular cyclopropanations with diazo compounds and phenyliodonium ylides: Synthesis and chiral analysis
Ghanem, Ashraf,Lacrampe, Fabienne,Schurig, Volker
, p. 216 - 239 (2007/10/03)
Different classes of cyclopropanes derived from Meldrum's acid (=2,2-dimethyl-1,3-dioxane-4,6-dione; 4), dimethyl malonate (5), 2-diazo-3-(silyloxy)but-3-enoate 16, 2-diazo-3,3,3-trifluoropropanoate 18, diazo(triethylsilyl)acetate 24a, and diazo(dimethylphenylsilyl)acetate 24b were prepared via dirhodium(II)-catalyzed intermolecular cyclopropanation of a set of olefins 3 (Schemes 1 and 4-6). The reactions proceeded with either diazo-free phenyliodonium ylides or diazo compounds affording the desired cyclopropane derivatives in either racemic or enantiomer-enriched forms. The intramolecular cyclopropanation, of allyl diazo(triethylsilyl)acetates 28, 30, and 33 were carried out in the presence of the chiral dirhodium(II) catalyst [Rh 2{(S)-nttl)4}] (9) in toluene to afford the corresponding cyclopropane derivatives 29, 31 and 34 with up to 37% ee (Scheme 7). An efficient enantioselective chiral separation method based on enantioselective GC and HPLC was developed. The method provides information about the chemical yields of the cyclopropane derivatives, enantioselectivity, substrate specifity, and catalytic activity of the chiral catalysts used in the inter- and intramolecular cyclopropanation reactions and avoids time-consuming workup procedures.
Rh(II)-catalyzed enantioselective cyclopropanation of olefins with dimethyl malonate via in situ generated phenyliodonium ylide
Muller, Paul,Ghanem, Ashraf
, p. 4347 - 4350 (2007/10/03)
(Chemical Equation Presented) Olefins are cyclopropanated with dimethyl malonate (1a) iodosylbenzene (Phl=O) and a Rh(II) carboxylate catalyst via an in situ generated phenyliodonium ylide (1c). Enantioselectivities of up to 90% for 4-bromostyrene and 98% for pent-1-ene have been observed with (S)-N-4-bromo-1,8-naphthanoyl-tert-leucine (4c) as the chiral ligand. The same catalyst was effective for olefin cyclopropanation with Meldrum's acid, giving cyclopropanes with 96% (with styrene) and 87% ee (with pent-1-ene), respectively.
