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)
INFLUENCE OF OLEFIN COORDINATION ON CYCLOPROPANATION SELECTIVITY
Catalyst-dependent differences in regioselectivity for cyclopropanation result from the degree of charge development in the transition state rather than from intramolecular collapse of a coordinated olefin.
Doyle, Michael P.,Wang, Linda C.,Loh, Kuo-Liang
p. 4087 - 4090
(2007/10/02)
PHOTOCHEMISTRY OF ALKYL HALIDES - VII. CYCLOPROPANATION OF ALKENES
The previously observed cyclopropanation of alkenes by irradiation of diiodomethane (1) in their presence has been studied in more detail and found to be a synthetically useful procedure which is significantly less subject to steric effects than the traditional Simmons-Smith method.The results from photocyclopropanation of a variety of alkenes are summarized in Tables 1 and 3-4.In a number of cases the photochemical procedure afforded improved results over the Simmons-Smith method, particularly with sterically congested alkenes.Cycloalkenes showed relative rates of photocyclopropanation as a function of ring size similar to those of the Simmons-Smith method (Table 5).However, the photocyclopropanation reaction exhibited steadily increasing relative rates with increasing substitution about the double bond-in contrast with the Simmons-Smith method (Table 6), in which steric effects offset increasing nucleophilicity of the alkene with increasing substitution.The α-iodocation 2 is suggested as the methylene transfer species.In the presence of lithium bromide cation 2 was trapped to afford bromoiodomethane.
Kropp, Paul J.,Pienta, Norbert J.,Sawyer, Joy A.,Polniaszek, Richard P.
p. 3229 - 3236
(2007/10/02)
Cyclopropanation of Terminal Olefins Using Diazomethane/Palladium(II) Acetate
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Suda, Minoru
p. 714
(2007/10/02)
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