Titanium(IV) Chloride Catalyzed Cyclopropanations of Alkenes Using Zinc Dust, Copper(I) Chloride, and Dihalomethanes
The addition of catalityc amounts of titanium(IV) chloride greatly facilitates the cyclopropanation reactions of alkenes with dibromomethane using zinc dust and copper(I) chloride in ether.The rate of reaction and yields of cyclopropane products obtained from alkenes not bearing Lewis acid sensitive functional groups are as good or better than those found by using dibromomethane with ultrasound promotion.They are also comparable to those obtained by using diiodomethane under various conditions.
Friedrich, Edwin C.,Lunetta, Steven E.,Lewis, Eric J.
Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes
Dinuclear Ni complexes supported by naphthyridine-diimine (NDI) ligands catalyze the reductive cyclopropanation of alkenes with CH2Cl2 as the methylene source. The use of mild terminal reductants (Zn or Et2Zn) confers significant functional-group tolerance, and the catalyst accommodates structurally and electronically diverse alkenes. Mononickel catalysts bearing related N chelates afford comparatively low cyclopropane yields (≤20 %). These results constitute an entry into catalytic carbene transformations from oxidized methylene precursors.
Zhou, You-Yun,Uyeda, Christopher
supporting information
p. 3171 - 3175
(2016/03/12)
Evidence for the cyclic CN2 carbene in solution
Diazirinylidene (c-CN2) is formally the simplest of the N-heterocyclic carbenes. The intermediacy of this elusive species in the fragmentation of butyl 3-bromodiazirine-3-carboxylate (1a) with pent-4-en-1-ols and their sodium alkoxides in DMF i
Hanzlova, Eva,Navratil, Rafael,Cejka, Jan,Boehm, Stanislav,Martinuis, Tomas
supporting information
p. 852 - 855
(2014/03/21)
Evidence for the cyclic CN2 carbene in the gas phase
3-Halodiazirine-3-carboxylic acids (c-CN2XCOOH, X = Cl or Br) were prepared from their esters and converted to the corresponding sodium salts. Collision-induced dissociation (CID) of the carboxylate ions led exclusively to the loss of CO2
Hanzlova, Eva,Va, Ji,Shaffer, Christopher J.,Roithov, Jana,Martinu, Tom
supporting information
p. 5482 - 5485
(2015/02/19)
Electrochemical Cyclopropanation of Alkenes Using Dibromomethane and Zinc in CH2Cl2/DMF Mixture
An efficient electrosynthesis of cyclopropanes from gem-dibromoalkanes and alkenes is achieved in a one-compartment cell fitted with a sacrificial zinc anode.The part played by the anodically generated Zn(II) in the coupling reaction is pointed out, and evidence for the existence of an organozinc species as intermediate is presented.
Durandetti, Sylvie,Sibille, Soline,Perichon, Jacques
p. 3255 - 3258
(2007/10/02)
Acetyl Chloride Promoted Cyclopropanations of Alkenes with Dibromomethane Using Zinc Dust and Copper(I) Chloride in Ether
Acetyl chloride strongly accelerates the cyclopranation reactions of alkenes with dibromomethane or diiodomethane using zinc dust and copper(I) chloride in ether and results in improved yields of cyclopropane products.