46319-71-5Relevant academic research and scientific papers
C(sp3)-H methylation enabled by peroxide photosensitization and Ni-mediated radical coupling
Vasilopoulos, Aristidis,Krska, Shane W.,Stahl, Shannon S.
, p. 398 - 403 (2021/05/06)
The “magic methyl” effect describes the change in potency, selectivity, and/or metabolic stability of a drug candidate associated with addition of a single methyl group. We report a synthetic method that enables direct methylation of C(sp3)-H bonds in diverse drug-like molecules and pharmaceutical building blocks. Visible light-initiated triplet energy transfer promotes homolysis of the O-O bond in di-tert-butyl or dicumyl peroxide under mild conditions. The resulting alkoxyl radicals undergo divergent reactivity, either hydrogen-atom transfer from a substrate C-H bond or generation of a methyl radical via b-methyl scission. The relative rates of these steps may be tuned by varying the reaction conditions or peroxide substituents to optimize the yield of methylated product arising from nickel-mediated cross-coupling of substrate and methyl radicals.
Solvent-free transesterification in a ball-mill over alumina surface
Chatterjee, Tanmay,Saha, Debasree,Ranu, Brindaban C.
experimental part, p. 4142 - 4144 (2012/08/28)
An efficient procedure for transesterification has been developed in a ball-mill in the absence of any solvent, acid/base or metal catalyst. A variety of methyl, ethyl, allyl esters have been transesterified to higher benzyl and other esters in high yields by this procedure.
Asymmetric hydrogenation of tri-substituted alkenes with Ir-NHC-thiazole complexes
K?llstr?m, Klas,Andersson, Pher G.
, p. 7477 - 7480 (2007/10/03)
An efficient chiral N-heterocyclic carbene ligand for the Ir-catalyzed asymmetric hydrogenation of largely unfunctionalized tri-substituted olefins has been developed. The Ir-NHC-thiazole catalyst is able to reduce a large variety of substrates with excellent conversions and good enantioselectivities with ee's ranging from 34% to 90%, depending on the geometry around the double bond of the substrates.
Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
RajanBabu,Nomura, Nobuyoshi,Jin, Jian,Nandi, Malay,Park, Haengsoon,Sun, Xiufeng
, p. 8431 - 8446 (2007/10/03)
Through a systematic examination of ligand and counterion effects, new protocols for a nearly quantitative and highly selective codimerization of ethylene and various functionalized vinylarenes have been discovered. In a typical reaction, 4-bromostyrene and ethylene undergo codimerization in the presence of 0.0035 equiv each of [(allyl)NiBr]2, triphenylphosphine, and AgOTf in CH2Cl2 at -56 °C to give 3-(4-bromophenyl) -1-butene in >98% yield and selectivity. Corresponding reactions with [(allyl)PdX]2 are much less efficient and less selective and may require further optimization before a viable system can be identified. Another useful protocol that gives comparable yield and selectivity involves the use of a single-component catalyst prepared from allyl 2-diphenylphosphinobenzoate, Ni(COD)2, and (C6F5)3B. Recognition of a synergistic relationship between a chiral hemilabile ligand (for example, (R)-2-methoxy-2′-diphenylphosphino-1,1′-binaphthyl, MOP) and a highly dissociated counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1,1-binaphthyl derivatives, prepared to probe the effect of hemilabile coordination on the efficiency and selectivity of the reaction, are also described.
